The first generation Seamaster 300, the ref. CK 2913-1, measured 39mm, and had straight lugs, a thin 60-minute bezel divided in 10-minute intervals, and broad arrow hands. The second generation, introduced seven years after the first, was 42mm, had chunkier twisted lugs, and also featured a wider bezel with hashes for every minute. Omega introduced two versions, the no-date ref. 165.024 and the ref. 166.024 with a date at three o’clock. The British armed forces gave the former model the nod.