The Sinn 103 St Sa is rated to 20 bar, and swimming is a reasonable use for a watch in sound condition when its screwable crown and push-pieces are secured. That specification is not a guarantee that a particular used or untested watch is still watertight, and Sinn’s reviewed technical documents do not establish that its chronograph pushers should be operated underwater.
What water-resistance rating does Sinn give the 103 St Sa?
Sinn’s October 2025 technical specification lists the 103 St Sa at 20 bar and says it meets the technical requirements of DIN 8310. The specification also lists a screw-fastened case back and screwable crown and push-pieces. Sinn’s October 2025 103 St Sa technical details
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An older Sinn technical sheet describes 20 bar as “200 m underwater depth.” That is the manufacturer’s stated pressure/depth equivalence, not a promise that every example can safely be used at that depth or that a watch retains its original sealing indefinitely. Sinn’s 103 series technical details
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For a sound watch with the screwable crown and push-pieces fully secured, swimming is a reasonable use of the 20-bar-rated 103 St Sa. The rating indicates substantial water-pressure resistance, but it describes the model specification rather than the present condition of an individual watch.
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- SIZE SELECTION: Available in 14mm 15mm 16mm 17mm 18mm 19mm 20mm 21mm 22mm 23mm and 24mm, please accurately measure your watch lug width and choose the right size
- WATCH BAND MATERIAL: Vintage Crazy Horse Leather lined with soft genuine leather, comfortable on your wrist, polished solid stainless steel buckle
- RETRO LOOKING: Natural crack appears when the leather is bent (NOTE: the black strap no crack), elegant and stylish. It's a loud little piece that express your style and personality
- BAND LENGTH: This strap is a regular length, suitable for wrists of 6" to 8", please refer to figure 6 for details
- BISONSTRAP SERVICE：If there are any question about the strap, please email us. REFUND or FREE REPLACEMENT, we will try our best to satisfy every customer
Sinn’s reviewed technical documents confirm that the controls are screwable; they do not explicitly approve swimming for every 103 St Sa variant or say that the chronograph pushers can be operated underwater. Keep the controls secured and do not operate the chronograph while the watch is submerged. These are prudent precautions, not a quoted Sinn instruction.
What should you check before taking one into water?
Confirm the watch’s condition
If the watch is older, has an uncertain service history, or may have been damaged or opened, do not rely on the model’s 20-bar rating alone. Have its water resistance checked by a qualified service provider before water exposure. The published specification is not an inspection or test of your individual watch.
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- Flexible and Comfortable: Made of tightly weave nylon fabric, this watch strap is soft, breathable, lightweight, washable and quick drying, paired with a sturdy brushed stainless steel buckle, suitable for various occasions
- Sturdy and Durable: The double-layer nylon is sewn, and the neat stitching enhances its aesthetic appeal and makes the strap more durable. The strap features laser cut holes to resist fraying and won't scratch your skin
- Easy to Change: The quick release springs make it a breeze to install on your watch, no tools required
- Applicable Wrist Length: The strap length is 75mm+125mm, thickness: 2.2mm, suitable for wrists ranging from 15.5cm to 20cm (6”-8”)
- Size Selection: Compatible with traditional or smart watches with standard lug width of 18mm, 19mm, 20mm and 22mm. Please accurately measure your watch lug width before ordering. Size=Watch Lug Width
Secure the crown and push-pieces
Before swimming, make sure the screwable crown and push-pieces are fully secured. Do not assume the rating makes unsecured controls safe in water.
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Sinn’s reviewed specification lists a 20 mm lug width. If you are considering a replacement or alternate strap, check the exact reference and attachment type before buying; lug width alone does not establish compatibility. Sinn’s October 2025 103 St Sa technical details
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- Band Width (Size): Fit for different kinds of watch that uses 18mm, 19mm, 20mm, 21mm and 22mm spring bars, please accurately measure your watch lug width and choose the right size
- Band Length: 75mm and 125mm. Thickness: 3mm. This strap is designed to fit wrists 6" to 8" (15.5cm-20cm), but watch geometry also impacts fit
- BISONSTRAP Service: If there are any question about the strap, please let us know. REFUND or FREE REPLACEMENT, we will try our best to satisfy every customer
Rank #3
- Flexible and Comfortable: Made of tightly weave nylon fabric, this watch strap is soft, breathable, lightweight, washable and quick drying, paired with a sturdy brushed stainless steel buckle, suitable for various occasions
- Sturdy and Durable: The double-layer nylon is sewn, and the neat stitching enhances its aesthetic appeal and makes the strap more durable. The strap features laser cut holes to resist fraying and won't scratch your skin
- Easy to Change: The quick release springs make it a breeze to install on your watch, no tools required
- Applicable Wrist Length: The strap length is 75mm+125mm, thickness: 2.2mm, suitable for wrists ranging from 15.5cm to 20cm (6”-8”)
- Size Selection: Compatible with traditional or smart watches with standard lug width of 18mm, 19mm, 20mm and 22mm. Please accurately measure your watch lug width before ordering. Size=Watch Lug Width
What the 20-bar figure does—and does not—tell you
- It tells you: Sinn rates the 103 St Sa at 20 bar and references DIN 8310 in its October 2025 specification.
- It does not tell you: whether an individual watch with unknown condition or service history still meets that specification.
- It does not establish: a specific instruction to operate the chronograph underwater or a blanket swimming approval for every variant.
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