Sinn &
Sinn &
Sinn &
Sinn &
Sinn &
Sinn &
Sinn &
Sinn &
Sinn &
Sinn &

Sinn 'On the Fly' Folding Extension H-Link

$159.99
/
  • Worldwide shipping available
  • Complimentary worldwide shipping insurance
Model

YOUR BRACELET IS NEVER THE PERFECT FIT

Sinn makes some of the toughest, most capable tool watches in the world — but even they missed this. Add it, and it’s perfect.

Morning: perfect. Afternoon: too tight. Evening: too loose. Heat, cold, and movement change your wrist — your bracelet can’t keep up.

On The Fly fixes that with instant, tool-free ±5 mm adjustment, completely hidden under your clasp. You’ll never see it, and neither will anyone else — except they’ll notice your watch always sits perfectly.

  • Always Perfect – Comfort on demand, in seconds.

  • Invisible Upgrade – Discreetly tucked under the clasp, preserving your watch’s original look.

  • Luxury Craftsmanship – Same high-grade stainless steel as Sinn, with a flawless aesthetic match.

  • Easy 1-Minute Install – Uses your existing screw and hex key; install once and adjust forever.

  • Reversible – Install once, remove anytime, no trace.

Once you try it, every other bracelet will feel wrong.

Tools Required

  • The hex key supplied with your Sinn watch (for hex bolts)
  • Push-pin or spring-bar tool
  • (Optional) Purple Loctite 222 low-strength threadlocker.

Installation Steps

1. Remove the clasp from the bracelet

  • Use a push-pin or spring-bar tool to depress the spring bar that connects the clasp to the bracelet.
  • Detach the clasp completely.

2. Remove the original diver’s extension

  • The Sinn diver’s extension is held in place by hex bolts.
  • Using your Sinn-supplied hex key, remove the bolts securing it to the bracelet.
  • Retain the original bolts — they will be used to install your On The Fly link.

3. Install the Steel Reef On The Fly Extension Link

  • Position the extension link where the diver’s extension was removed.
  • Using your original Sinn hex bolts, secure it in place with the hex key.
  • (Optional) Apply a very small drop of Loctite 222 to the bolt threads before tightening.

4. Reattach the clasp

  • With the extension link in the open position, slide the clasp’s connector into the extension link’s folding arms.
  • Use the spring-bar tool to depress the spring bar and secure the clasp back onto the bracelet.

About Bracelet Fit

  • The OTF replaces the Sinn diver’s extension, which is designed for wetsuit use and not daily micro-adjustment.
  • You may need to adjust your bracelet attachment point along the clasp’s micro-adjustment holes to achieve your perfect fit.

We pride ourselves on the exceptional quality and craftsmanship of our products, each inspired by OEM standards. Offering a Satisfaction Guarantee, we invite you to experience the quality firsthand. If you're not completely satisfied, we welcome returns for a full refund or exchange, ensuring a risk-free purchase.

We are not affiliated, associated, endorsed by, or in any way officially connected with any watch brands. Our parts are aftermarket accessories, designed with quality and precision, that may be compatible with and fit a variety of watch models. Additionally, be aware that installing our products may void any active warranties or guarantees on your watch.

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Customer Reviews

Based on 3 reviews
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33%
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I
I.Z.

Excellent fit and quality

P
Pierre (Madrid, ES)
SINN 104W

Good stuff. It is a replica of the "easy link system" from Rolex and works perfectly on my Sinn 104 bracelet.
Note that you should be familiar with bracelets and links replacements to set this Extension properly.
I had to remove the diver extension to install this one but that's not a problem for me.
For my size of wrist, I did place the easy link on the last micro adjustment, and you can notice a slight gap then between the clasp and the H link. Nothing to worry about.
If you place it on the second micro adjustment, the gap simply disappears.
Overall, very positive, I can now use my bracelets comfortably even if my wrist changes during the day.

B
Ben P. (Fort Lauderdale, US)
Finally a perfect fit on my H-link

Gotta say I wasn’t sold on the value when I first opened the package. It wasn’t clear looking at the link uninstalled that it would work as promised. It also took me a minute to figure out installation as the instructions on site aren’t specific to Sinn. You do have to remove the diver’s extension to fit the Steel Reef link on, FYI.

But once I got it on the bracelet, I immediately realized how much of a game changer this little steel contraption is. I love my Sinn and I love the H-link but have struggled with a good, all day fit. I’ve either had it on the tightest micro adjust and still dangling off my wrist, or with one link less on the loosest micro hole and choking my wrist at the slightest swell.

Now I have a perfect fit in the middle micro adjust and the extension gives me the room to swell - and with the Steel Reef link attached to the middle micro hole, you can’t see the extension at all.

Product itself is a solid 5/5. Giving 4/5 to the review because installation instructions could have been clearer + $159 is a lot of money to upgrade a bracket that costs $380 brand new.

But overall could not be more pleased! Thank you, Steel Reef!

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