Sinn EZM4 Review

Oct 04, 2016,04:11 AM

This is my review of the Sinn EZM4.

I won’t detail the history of this great lineup of EZM models from Sinn as many did it well better than I would. For example, you can read good one from my French mate Grinhu:


Here is a short description from the Sinn website:

« Mission Timers (Einsatzzeitmesser or EZM) are watches which have been specially developed for a particular purpose. They always offer excellent readability. This means: the form is always dictated by the function and handling requirements.”

The EZM4 is a watch with vintage style, very 1970 ish, using a case already seen on some Heuer watches and close to those of the Speedmaster Mark II or Mark IV.


This case isn’t that elegant or delicate. It’s a chunky massive piece. But the heft is quite controlled with only 15mm while most of Sinn chronographs are closer to 17mm.


On my watch, made from the last batches, the case looks to be ready to accept an Argon capsule but finally has a screw to fill the hole.


Bracelet is somehow integrated into the case and very comfortable. I have absolutely no intent to wear it on another strap right now. The deployant buckle has micro adjustment holes for a perfect sizing.

For a full feature list of this watch, the best is to look at the archive page here:

This EZM4 embeds what is considered one of the best chronograph caliber, the Lemania 5100. Not for its refinement but for its feature and conception. It has a central minute counter which is extremely useful when you actually use the chronograph and need to know the time elapsed at a glance. This caliber is also very shock resistant and can be used and abused without fear.

A good review of this caliber here :

Whilst we largely find this caliber in watches with its hour and 24 hours counters, on the EZM4, Sinn decided to keep only what matters to its primary application.


I am used to this caliber with my previous Sinn 142 and completely fall in love with the immediate reading of the elapsed time. It’s a joy and I don’t understand why the Swatch Group stopped the production. Maybe today there is no room for a chronograph movement that is not beautiful to look at and maybe the real tool watches don’t exists anymore.


So the EZM4 is a proper tool watch, from the end of this era probably, and is designed to be used by firefighters and other emergency workers.

We can find similarities with other EZM watches like the left side crown and pushers, white hands and a black dial and not important information are written in red to not disturb the reading of the time. Thus, we can notice Sinn choose to keep the date in white while other EZM models like the EZM1 have a red date too. I think this one doesn’t have to be used by commando members and stealth is not the priority.

And that’s a good thing because Sinn is using the dial to help users of SCBA (Self Contained Breathing Apparatus) like firefighters.

The SCBA are generally equipped with a 6 liter volume tank, inflated at a pressure of 300 bars. As for the scuba diving tanks, this is compressed air (78% oxygen, 21% nitrogen) and not pure oxygen because it would be extremely inflammable.

Once released at a pressure of 1 bar and following the Boyle-Mariotte law, we have a volume of air equivalent of : V2=P1xV1/P2=1800 liters.

As a man in full motion use a maximum of 100 liters of air per minute, we obtain an autonomy of 18 minutes which, stripped by a security margin of 10%, gives a 15 minutes autonomy to the user of this equipment.

We better understand now the red and yellow scale on the dial of this EZM4.

The user of thie SCBA is safe during the first 15 minutes. But then, he’s exposed to the risk of being short of air and being pushed to breath the dangerous atmosphere around him (vapors, dust, toxic gas…).

A second tool comes under the form of a base 15 pulsometric scale. A useful feature for emergency workers and doctors but becoming rare in modern chronographs.

Last feature is the classic divers extension of the bracelet which is welcome to adjust the watch upon the firefighter heavy suit.

While there have been around 3300 EZM1 watches produced, Sinn doesn’t want to communicate on the production number of the EZM4. Regarding the relative small number of these on forums and sales and his shorter period of life in the catalog, I think there is less than 1000. Maybe even less than 500 around.

This model left the catalog in 2004 and mine has been sold in May 2005, confirmed by the customer service archives.

Its condition is incredible. Not a single dent, only very small scuffs. And it’s working like a charm. Obviously it has not been used in conditions described before !

When I received it I was very happy of course.

It’s only after a while, looking at it in all angles, that something strange appeared to me… How lightweight this watch is! Would it be a very good fake? Uh…

A quick glance at the caseback and I found the answer.

« Reintitan » ?

To my knowledge this watch was only made in steel. This is also how it’s described in the archive link on Sinn website. But a longer search on the Internet brought the fact that a small batch may have existed in titanium!

So I contacted Sinn to ensure this one wasn’t an aftermaket customization of a 157 Ty and to confirm the truth about this Titanium batch. The answer is that there has been a small batch made in titanium for a specific customer. A batch of 25 units (reference 157.063, 157Ti EZM4) and this one is part of this special batch!

Titanium gives is a soft feel and a different color from a steel model. The color is close to steel in bright light but can transition to a charcoal tint under dark light. It’s really beautiful.

For the weight, adjusted to my wrist, it tops at 100 grams and the head only weights 86 grams.

Thanks for reading !

More posts: SpeedmasterSpeedmaster Mark II

  login to reply

Comments: view entire thread


Thank you for the review Gargamel.....

 By: watercolors : October 4th, 2016-04:44
EZM4 is a great watch with nice features. A worthy addition to a watch collection. This one (657) is saying hello, it is not a firefighter watch but I heard it is a choice of a Police Officers while on the job. I wear it casually as a day to day companion...  

Nice review, thanks

 By: Alle : October 4th, 2016-06:18
My 556 says hi this morning ...