Developed in collaboration with Germany’s elite counter-terrorism and special forces unit, GSG 9, the Sinn 403.GSG9 HYDRO EZM2 is a professional mission-timer built with robust capabilities. EZM stands for Einsatz Zeit Messer, which translates to English as Mission Timer.

Its defining innovation is Sinn’s HYDRO technology: the entire case is filled with oil, eliminating internal air and making the watch extremely legible underwater from every angle, fog-proof, and immune to crushing pressure differentials. The result is an instrument trusted by professionals whose lives depend on it.

It's a really cool watch, and one we couldn't pass up when it was offered to us with original box and papers in nearly new condition.

Why quartz—and why it matters:
To achieve this feat, Sinn turned to quartz. An oil-filled case requires fluid to permeate every recess of the movement as well as the case, something a mechanical escapement cannot tolerate. (Brands like Ressence get part-way there with half-filled displays, but the mechanical heart remains sealed off in a dry capsule. Sinn completely submerged the quartz movement itself in oil.)

How deep is "too deep"?
HYDRO technology makes the case itself effectively unconcerned with depth. Sinn later certified the UX (EZM 2B) as pressure-resistant to an extraordinary 12,000 meters—deeper than any point on Earth’s oceans. Ironically, it isn’t the case but the quartz movement that sets the limit: rated to 5,000 meters, which is why “5000 m” appears on UX dials. The 403.GSG9 demonstrates the same underlying innovation, giving it credibility few other divers can match.

Details that matter in the field:
The crown sits on the left side at 10 o’clock, an ergonomic decision that keeps it from digging into the wrist, catching on gear, or being knocked in mission use. A thermal-expansion membrane on the caseback absorbs the natural volume change of the oil across extreme temperatures, keeping the crystal safe and the watch reliable. With oil in contact with the underside of the sapphire crystal, reflections vanish and underwater readability is unmatched.

Our Hyrdro:
As I mentioned, our example is in gorgeous original condition, a 9.7 out of 10. The back has some tiny remnants of wear - otherwise the watch presents as like new. Its dial and crystal both present like new.

It comes complete with its original Sinn “Einsatzzeitmesser 403.GSG9 HYDRO” presentation box and papers—rare to find intact and highly prized among collectors.

A Master Watchmaker has installed a new battery and performed any needed servicing making. For the finishing touch we have installed a brand new calfskin strap and meticulously detailed it making it ready for immediate enjoyment.

Included with the purchase is a one-year C.O.T. international warranty on the movement and its function and a full-page custom printed Connoisseur of Time Certificate of Authenticity.

Why collectors want it:
Among the countless “dive-inspired” watches, only Sinn rewrote the medium itself by filling the watch with oil. The result is a professional instrument with peerless underwater performance, mission pedigree, and a design built around solving real problems. Combined with its nearly new condition and complete set, this 403.GSG9 is one of the more compelling and conversation-worthy divers available.

Your watch is important to us, and we will take care of it for its lifetime. We provide the best after sale care in the business with an extremely experienced team of four Master Watchmakers all of whom each have over thirty-five years of experience and a large number of parts. One used to be the watchmaker for an authorized Rolex dealership and was given training by Rolex at their Beverly Hills Service Center.

Brand name: Sinn
Model: 403.GSG9 HYDRO EZM2 / 403.0745
Features: Hours, Minutes, Quick-Setting Date, Sweep Seconds, Deep Diver, Elapsed Time Bezel
Dial color: Black
Movement: ETA 955.612 based Sinn caliber high-accuracy quartz, chosen for torque and reliability in an oil-filled environment
Calendar: Date
Crown: Original Sinn, screwed down
Water resistant depth (originally): Sinn specifies 50 bar for the EZM-class HYDRO; proven by later UX to withstand pressure equivalent to 12,000 m (movement rated to 5,000 m)
Bezel material: Stainless steel
Bezel Function: Unidirectional rotating racheting diver's elapsed time
Case material: Bead-blasted steel by SUG
Case condition: In gorgeous original condition, a 9.7 out of 10.
Case diameter: 41 millimeters excluding crown and guards
Crystal: Sapphire, flat, scratch-free
Band material: Leather
Band: Calfskin leather, fully stitched, padded, brand new and unworn
Band width: 20 millimeters
Serviced: A Master Watchmaker has installed a new battery and performed any needed servicing making. For the finishing touch we have installed a brand new calfskin strap and meticulously detailed it making it ready for immediate enjoyment.
Warranty: 1-year C.O.T. international warranty. Your watch is important to us, and we will take care of it for its lifetime. We provide the best after sale care in the business with an extremely experienced team of four Master Watchmakers all of whom each have over thirty-five years of experience and a large number of parts. One used to be the watchmaker for an authorized Rolex dealership and was given special training by Rolex at their Beverly Hills Service Center.
Box/Papers: BOX - Original Sinn fitted box; PAPERS - Original papers/certificate and booklet
Returns: 7 days full refund. 100% satisfaction guarantee

We offer a 100% satisfaction guarantee for all of our watches. If you are in any way unsatisfied with the watch we will fully refund the purchase price anytime within 7 days after the watch has been received. Our goal is to exceed our client's expectations throughout the buying experience.

All watches are packaged carefully and mailed double boxed in specially constructed, reinforced shipping boxes designed for high value items. All watches are sent fully insured with signature required. Most of our domestic shipping is done through FedEx. At times we will also use USPS Express Mail, and we can accommodate most requests for your preferred carrier. International shipments are sent USPS International Express Mail or FedEx.

The purchase price will be the declared value of the merchandise on any required customs forms. The payment of all customs duties, tariffs, and taxes are the responsibility of the buyer.

Also note that water resistance of vintage watches can no longer be guaranteed and is not covered under the watch's warranty. We do not recommend getting a vintage watch wet, even one that was originally designed to be waterproof.

To get an idea of how this watch will look on the wrist, please use the Watch Sizing Guide

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