This is a wonderful vintage Certina Club 2000.
Although it’s one of the lower grade Certinas, it’s still beautifully finished and it has a solid stainless steel case.
All the Certina in-house movements that I’ve encountered are great performers and you can accurately regulate them with the micro-regulator.
Sadly, the 25-66M movement in this Certina wasn’t running.
Certina produced the 25-66M from ’75 till ’77. This Certina has a serial number that consists of 9 digits and that indicates that it’s a ’74+ piece so it’s all adding up.
There were some problems with winding because you could wind it until forever without it ever building up any resistance. If you think that sounds like a broken mainspring, you’re right!
It also had some problems with water resistance because at one time the crystal fogged up during an exceptionally hot day.