Case back




This sterile (polished) case back can be used on most Seiko models. It is made of 316L stainless steel. It is delivered without a gasket (you should use the gasket from the case back it replaces).

You can choose “high” thread, to be used on most Seiko5 models (those have a low movement holder, approx. 3mm) and when you use the grey NH3x movement holder. It is also available with “low” thread (good for most Seiko divers, those have a high movement holder, approx. 3.5mm).

This caseback does not make your water resistance less if you have a diver and you use your original rubber gaskets. And also, if you have a 10atm watch, using this case back will not increase the water resistance, the water resistance of 10atm is influenced by the crown gasket and glass gasket too. So this case back is not to be used to increase the water resistance of your watch!

One nice aspect of this sterile case back is that you can apply engraving on it, nowadays many engraving companies are not willing to engrave a watch case, but on this loose case back, they can put everything you want!!


(The new SRPD-Sports based on SKX-cases need the high thread (4R36-07G0 and 4R36-08L0 case codes).


The case back with low thread fits on the SNXS79! (7S26-0480 watch case) and lowers the watch a bit.

WATCH OUT! There is an issue with the case back with low thread and the 7S26-0480 watch; the movement sometimes stops (even with a rotating rotor).
We are makking new case backs without this issue (and those are even lower), people who have bought this brushed case back will receive the new version when it is available (ETA is end of November).

The case back with low thread also fits on the SNKL41 (7S26-01V0 watch case), but the OEM case back is not really high so there is not much to gain here.
The case back with the high thread fits on the Seiko5 models with 7S26-02W0 on the case back (like SNKE49, SNKK07 and the like). Here the OEM case back is already pretty low, so there is not much to gain.

When you are not sure, put the case-code of watch you want to use it in the order-comment, and I will ship the correct case back.
You can find the case code engraved on the case-back, it looks like xxxx-xxxx, like 7S26-0020 or 4R36-07G0).

– sold without case back gasket –