The 56GS, released in 1970, presented a smaller form factor via an automatic caliber measuring just 4.5mm in height. Despite the smaller size, and lower frequency of 4hz / 28,800bph vs the 5hz 36,000bph of the 61xx and 45xx, the watch retained the high precision of its predecessors, and was even believed to be more robust in terms of wear and shock protection.