Just got my Seiko “Helmet” chronograph from a tune-up. At the same time, I changed the original, very tatty, strap for a new rubber one. I think it matches the design of the watch quite well.
This is one of the most famous Seiko chronographs from the mid 70’s. Commonly referred to as the “Helmet” or “Darth Vader” due to the peculiar shape of the case (see the 2nd photo). For any watch geeks out there this is model 6139-7100, so it uses a 6139 caliber – automatic chronograph with a 30min register. This is one of the very first automatic chronograph movements, along with the ones from Heuer and Zenith, all born in 1969.