cazalea[Seiko Moderator]
20986
They made several series of these regulator diver watches
I had the earlier version, liked it and looked around for the beefier alternative model, but couldn't find any. Other than the lume falling out of the hands, it was fine.
I got mine used in 2008, and sold it about 2012. This is the one I was looking for - about 40 mm
There were non-diver versions as well, in round and tonneau cases.
This titanium TT1 was a bit too gaudy for me and full-sized at 44mm
Oris made these watches in various sizes - here's a 47mm

and a 49mm
Here's the 44mm in titanium, bracelet, strap, accessories, etc. - complete kit on eBay right now