Vintage Sheffield All Sport

Today I'm wearing another vintage watch, a Sheffield All Sport model. This watch was originally my grandfather's and was probably purchased sometime in the 1960s. It's styled like a diver and says "Waterproof" and "Shock Resistant". I wouldn't consider it a proper diver because it lacks a specific depth rating and the bezel is bidirectional. It probably was more of an all-purpose outdoors watch, suitable for swimming, boating, camping, etc. It is fitted with a Tropic brand strap, but I don't know if it was original or fitted after the watch was purchased. I know that NOS Tropics are relatively expensive these days, so it's nice to already have one on a period watch. It is Swiss Made, but I haven't had it open so I don't know what movement it has. I should probably have it serviced as it does start and stop randomly, especially if it's not being worn. I doubt my grandfather ever had it serviced so it's probably about time.