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SlimeVR’s Butterfly Trackers are no longer in crowdfunding: the campaign ended on March 19, 2026, after SlimeVR said it reached its goal in about 30 hours. As of August 18, the Crowd Supply page lists the trackers for preorder, with current orders estimated to ship October 30, 2026. That is an estimate, not a guaranteed delivery date. The main draw is a thinner, lighter design and manufacturer-claimed battery life of more than 48 hours; the headline 100–200 Hz refresh rate remains a target, not a finalized specification.
What Butterfly Trackers are—and what makes them different
Butterfly is SlimeVR’s ready-made take on the lightweight “Smol” tracker concept. Like SlimeVR’s other trackers, it uses inertial measurement units (IMUs) to measure each unit’s rotation. SlimeVR Server combines those readings with the headset reference, body proportions and calibration to estimate body-part positions. It does not use cameras or base stations, but it is still an IMU system: it is not optical-grade positional tracking and should not be described as drift-free.
The hardware uses an nRF52833 microcontroller and a TDK ICM-45686 IMU. Its “butterfly” form puts the circuit board and battery in separate small housings joined by a flexible band. SlimeVR lists the tracker as less than 7 mm thick and less than 10 g, intended to sit closer to the body than a rigid, bulky enclosure. The thin profile may be useful when sitting or lying down, mounting a tracker at the hip or lower back, or wearing units under loose clothing. Comfort remains personal; SlimeVR’s descriptions of the trackers as nearly unnoticeable or exceptionally comfortable are marketing claims, not independent findings.
The design is intended to make long sessions and flexible mounting easier. Listed attachment options include straps, hook-and-loop patches and belt clips; iron-on clothing patches are available separately. This is a physical-design upgrade, not a new tracking principle.
#1 Best Overall
- SlimeVR-Compatible FBT Kit: Designed for SlimeVR-compatible full body tracking setups for VRChat, SteamVR, and Quest PCVR. 6-point configurations to match your preferred avatar tracking setup.
- LSM6DSV IMU Motion Sensors: Each tracker uses an LSM6DSV IMU motion sensor to support responsive pose tracking, smooth avatar movement, and stable long-session performance for social VR, dancing, streaming, and motion capture-style use.
- Anti-Slip Straps with Quick-Release Buckles: Includes anti-slip straps matched to different body positions: longer straps for torso areas, medium straps for thighs, and short straps for lower legs, ankles, or feet. Quick-release buckles make attachment and adjustment easier.
- Compact Black Trackers with Complete Accessories: Compact black trackers with USB-C charging, built-in 800 mAh rechargeable battery, up to 9 hours of use, charging accessories, USB data cable, and carrying case for storage, setup, and daily organization.
The radio trade-off: no Wi-Fi setup, but a required dongle
Earlier official SlimeVR trackers communicate over 2.4 GHz Wi-Fi. Butterfly instead uses Nordic Enhanced ShockBurst (ESB) through a dedicated USB receiver. That means the trackers do not need to join your Wi-Fi network, and SlimeVR says the radio approach reduces power use. The receiver supports up to 10 Butterfly Trackers at once; SlimeVR lists more than 10 metres of reliable range with its tuned antenna.
The trade is that the Butterfly dongle is mandatory. A standalone tracker purchase does not include it, and a generic Bluetooth receiver is not a substitute. You also need a free USB port or a suitable adapter for a host device that lacks one. Range is more bounded than ordinary Wi-Fi coverage, so receiver placement and the size of your play space matter. “No Wi-Fi required” refers to the tracker-to-host radio link; a particular app or standalone workflow may still use network communication, such as OSC between SlimeVR Server and VRChat.
Battery, refresh rate and performance claims
- Battery: SlimeVR lists a built-in 90 mAh battery, USB-C charging and more than 48 hours of playtime. Deep sleep is part of the rationale for its suggestion that someone playing a few hours a day might charge weekly. Those are manufacturer specifications and usage estimates, not a guaranteed runtime. Radio conditions, firmware, update settings, motion and sleep use can affect battery life. SlimeVR’s documentation gives a broad 40–60-hour range for Smol/Butterfly-style trackers and roughly 18–20 hours for older official Wi-Fi trackers; that is useful context, not a controlled test of final Butterfly production units.
- Refresh rate: the product page lists a 100–200 Hz target and explicitly says the specification is not finalized. Treat it as provisional, not a guaranteed operating rate.
- Latency and precision: SlimeVR lists latency under 15 ms and precision of 1–5 cm. The company cautions that precision depends on setup. These are product claims, not independently measured production results presented here.
- Coverage: SlimeVR lists 360-degree coverage and more than 10 metres of range. Coverage does not remove the limitations of an IMU system.
A higher update rate is not the same thing as more accurate avatar movement. It does not eliminate drift, correct a poorly mounted tracker or turn estimated body position into optical six-degrees-of-freedom tracking. SlimeVR says Butterfly uses the same general tracking technology and IMU family as its current trackers, and describes its drift-reset behaviour as comparable. The company also says the “stomp bug” associated with earlier V1.0/V1.1 hardware does not affect Butterfly; that does not mean all drift or calibration issues disappear.
Choose by tracker count, not the bundle name
The number of trackers determines which body points you can track. “Full body” does not mean every body part receives both position and rotation data.
Rank #2
- Full-Body Tracker: Track the physical presence of your entire body within the virtual environment. Capture full-body motions with as few as 3 trackers (Support for SteamVR BS1.0 and BS2.0).
- VR Accessory Tracking: Enable the tracking of real-world objects and VR accessories to increase the realism of your simulation or training experience.
- Light Weight: Lighter weight for easier handling, improved comfort, and more uses with your VR set. Your favorite VR tracker just got even more versatile (15% lighter than VIVE Tracker 2018).
- Longer Lasting Battery: Work, train, and create for longer with up to 7.5 hours of battery life (Up to 75% longer than VIVE Tracker 2018).
- Expand Your View: 240° field of view
| Bundle | Price | What the tracker count adds |
|---|---|---|
| Core Set | $279 | Six trackers: hip, knees and chest position/rotation, plus foot position—but not foot rotation. |
| Enhanced Core Set | $364 | Eight trackers; adds foot rotation. |
| Full-Body Set | $449 | Ten trackers; adds elbow tracking. |
| Sakura Special Edition | $499 | Ten translucent-pink trackers, charging dock, accessories and special packaging. |
| Motion Capture Set | $788 | Seventeen trackers for chest, waist, knees, ankles, feet, upper and lower arms, shoulders, hands and head; includes 20 iron-on patches. |
For casual social VR, six or eight may be enough. Choose the eight-tracker set if foot rotation matters; the ten-tracker set adds elbows, not every possible mocap point. The 17-tracker configuration is aimed at more detailed capture. SlimeVR’s listed bundle prices do not include displayed shipping: the Crowd Supply page shows $8 in the U.S. and $18 worldwide. Taxes or other import charges may also depend on destination.
Individual trackers, upgrades and accessories
- Feet Upgrade (two trackers): $85
- Elbows Upgrade (two trackers): $85
- Head Upgrade (one tracker): $45
- Single Butterfly Tracker: $40
- Butterfly Dongle Kit: $19
- Charging Dock: $49
- Twenty iron-on patches: $20
- Two belt clips: $10
Check what is already in your kit before ordering add-ons. A single tracker does not include the required dongle or a complete mounting system, so it is not automatically a drop-in replacement for an older SlimeVR unit. The dock can charge up to 10 trackers simultaneously, but does not include an AC adapter. It is most useful for larger sets or frequent charging—not an essential purchase for every six-tracker buyer.
Compatibility and setup
SlimeVR lists support across SteamVR, OSC, VMC and OpenXR-related workflows, as well as VRChat, Resonite, ChilloutVR and LIV. It also names VTubing tools including VNyan, Warudo and VSeeFace, and mocap workflows in Blender and Unity through relevant plugins or BVH recording. The ecosystem is broad, but that does not guarantee identical features or plug-and-play setup in every application.
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Standalone workflows are supported for platforms including Meta Quest and PICO VR, but the host may need a USB adapter for the dongle. For standalone VRChat, SlimeVR documentation describes configuring OSC so SlimeVR Server can send tracking data to VRChat. Check the relevant app and headset setup before buying; the trackers themselves are only one part of the chain.
Rank #3
- Precise Full Body Motion Capture: Equipped with LSM6DSV inertial sensors, this slime vr full body tracking system delivers smooth, low-drift motion tracking that accurately mirrors your body movements in real time. Each of the six lightweight vr trackers maintains stable orientation even during fast-paced games and extended dance sessions
- Extended Play with 9+ Hour Battery: Each tracker runs for over 9 hours on a single charge, allowing uninterrupted vr full body tracking across multiple sessions. Whether you are exploring open worlds or attending virtual events, the long battery life keeps you immersed without frequent charging breaks
- Secure & Comfortable Strap System: Adjustable anti-slip straps in multiple sizes hold the slime trackers firmly in place on your ankles, waist, and chest. The soft, breathable material prevents slipping during active movement while staying comfortable enough for all-day wear
- Broad Headset Compatibility: These vr trackers connect seamlessly with SteamVR, Meta Quest, PICO, and Valve Index headsets. Quick pairing and straightforward calibration let you jump into supported VR titles across popular platforms with minimal setup time
- Lightweight & Low-Profile Build: Designed to be worn without distraction, each slime tracker features a compact housing that sits close to the body. The slim form factor reduces bulk under clothing and keeps the trackers unobtrusive during both casual and competitive vr full body tracking sessions
How Butterfly compares with older SlimeVR and alternatives
Compared with older official SlimeVR trackers, Butterfly’s clearest changes are its thinner, lighter construction, longer advertised battery life and dedicated low-power receiver instead of Wi-Fi. It retains the basic IMU-based approach and its need for calibration and drift management. Existing owners who are happy with their tracking may value the comfort or battery changes more than a different tracking experience.
DIY Smol trackers use the same broad lightweight concept and may suit electronics hobbyists who want customization or to source and assemble hardware themselves. That route also means handling parts, assembly, firmware, radio setup and troubleshooting. Butterfly is the finished-product option for people who would rather buy a ready-made system.
HaritoraX 2 is another IMU-based option, with Shiftall advertising LiDAR-assisted ankle sensing, long battery life, optional elbow and foot tracking, and Bluetooth LE or a dedicated dongle. Its Japanese product page lists ¥39,999 tax included; regional availability, software and accessory access may be less convenient outside Japan. See Shiftall’s product page for its current details.
Sony mocopi offers a more conventional branded hardware and software experience and may appeal to people already invested in Sony’s ecosystem. It differs in sensor configuration and ecosystem from SlimeVR’s open-source and DIY-oriented approach. See Sony’s mocopi product page for current compatibility and product information.
Rank #4
- Precise Full Body Motion Capture: Equipped with LSM6DSV inertial sensors, this slime vr full body tracking system delivers smooth, low-drift motion tracking that accurately mirrors your body movements in real time. Each of the six lightweight vr trackers maintains stable orientation even during fast-paced games and extended dance sessions
- Extended Play with 9+ Hour Battery: Each tracker runs for over 9 hours on a single charge, allowing uninterrupted vr full body tracking across multiple sessions. Whether you are exploring open worlds or attending virtual events, the long battery life keeps you immersed without frequent charging breaks
- Secure & Comfortable Strap System: Adjustable anti-slip straps in multiple sizes hold the slime trackers firmly in place on your ankles, waist, and chest. The soft, breathable material prevents slipping during active movement while staying comfortable enough for all-day wear
- Broad Headset Compatibility: These vr trackers connect seamlessly with SteamVR, Meta Quest, PICO, and Valve Index headsets. Quick pairing and straightforward calibration let you jump into supported VR titles across popular platforms with minimal setup time
- Lightweight & Low-Profile Build: Designed to be worn without distraction, each slime tracker features a compact housing that sits close to the body. The slim form factor reduces bulk under clothing and keeps the trackers unobtrusive during both casual and competitive vr full body tracking sessions
FluxPose is positioned as an occlusion-free 6DOF system and makes drift-free positioning claims, using a different tracking approach. It may interest buyers prioritizing positional accuracy and foot or object tracking over Butterfly’s price, battery claims or SlimeVR ecosystem; it is not simply a cheaper substitute. Compare details on the FluxPose site.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Open ecosystem, with one important caveat
SlimeVR describes Butterfly as open hardware with open-source software and publishes its server, drivers, Smol firmware and dongle firmware through its GitHub organization and documentation. The relevant ecosystem uses MIT and Apache 2.0 licensing. However, SlimeVR’s product page said the official Butterfly hardware design would be released after finalization. Anyone buying primarily to inspect, repair or manufacture from the final hardware files should verify that those files have since been published.
Campaign history and preorder risk
SlimeVR announced Butterfly in June 2025. A November 2025 project update described PCB Revision 10 and ongoing work on power efficiency, antenna tuning, firmware, onboarding and manufacturing readiness. The Crowd Supply campaign launched February 9, 2026; SlimeVR said on February 13 that it funded in about 30 hours. It closed on March 19, and the product page now lists preorders at $1,379,220 raised against a $180,000 goal, with 3,155 backers and 766% funding.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchStrong campaign funding and SlimeVR’s experience manufacturing and shipping earlier trackers improve the delivery case, but they do not guarantee schedule or final performance. The company identifies component supply, tariffs, certification, antenna tuning and final design as risks. The current October 30, 2026 shipping estimate has replaced an earlier August 31 estimate reported during the campaign period. Treat the date as a live estimate, particularly if you need trackers for a specific event.
Best Value
- Precision Virtual Reality Tracking: Meet the VR tracker for standalone devices. Use a VIVE Wireless Dongle to connect up to 5 VIVE Ultimate Trackers and effortlessly bring real-world movements into virtual or mixed reality.
- Compatibility: Get full-body tracking on HTC VIVE XR Elite and VIVE Focus Series, with support for all SteamVR PC VR headsets including Meta Quest, Valve Index, PS VR 2, and more.
- Precision in every move. Meet the VR tracker for standalone devices. Use a VIVE Wireless Dongle to connect up to 5 trackers (1) and effortlessly bring real-world movements into virtual or mixed reality. (2)
- Unlock a new dimension of movement and freedom. The first all-in-one positional tracker from HTC VIVE uses AI-powered self-tracking to redefine VR experiences.
- Pinpoint accuracy in a compact form. VIVE Ultimate Tracker employs two wide-FOV cameras and computer vision for instant spatial recognition, keeping virtual and physical movements in sync. (2) Its sleek, balanced design offers optimal functionality and comfort throughout use.
There is also no independent final-product performance test established by the specifications above. A buyer who needs verified runtime, a finalized refresh rate or proven production-unit behaviour may prefer to wait for customer or independent reviews rather than preorder on the strength of headline figures.
Who should consider Butterfly?
Butterfly is a sensible candidate if you already want SlimeVR-style IMU full-body tracking and prioritize a thin, light form, fewer Wi-Fi setup steps, long advertised battery life or flexible mounting. It may also suit existing SlimeVR owners who want additional points for feet, elbows or mocap.
Wait or look elsewhere if you require drift-free or optical-grade position, a guaranteed final refresh rate, immediate retail stock, a large receiver range, or a setup with no dongle, calibration or software configuration. Before ordering, confirm your tracker count, USB adapter needs, shipping and local charges, and whether the current estimated delivery works for you. The official Crowd Supply listing is the place to check live bundle availability and shipping estimates.
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