1966 Rolex Submariner (Ref. 5512) "Meters First"

The Rolex Submariner reference 5512 is the embodiment of the classic dive watch. The 5512 is simple yet sophisticated and rugged whilst becoming increasingly more uncommon and collectible. ref 5512 was first introduced in 1958 and ceased production in late 1978. The Rolex reference 5512, like the 5513, is a purpose-built dive watch that lacks the date function. 

The defining difference between the Rolex Submariner ref. 5512 and 5513 is the caliber of the movement. Both references began life with the Rolex cal. 1530 movement, but the 5512 soon adopted the chronometer-certified cal. 1560 movement, and later the cal. 1570 movement. Shortly after its inception, and with the integration of these more advanced movement calibers, the Rolex ref. 5512 adorned the iconic 4-lines of text on the dial, in the notation of its chronometer-rated timekeeping capabilities. This is the only visible differentiator of the ref. 5512 from the ref. 5513 and the most common method collectors use to identify between the references, as the ref. 5513 is classically known for its 2-lines of text. The ref. 5512 is much rarer than the 5513, as it was more expensive to produce and not as popular for its retail price. Its said that for every ten 5513s made in the 1970s, one 5512 was made

The depth rating began appearing on Submariner dials in late 1955 and was standard on all models by 1956. Early depth ratings were printed with the rating meters first, followed by the number in feet. This continued until early 1970 when Rolex made the switch to a feet-first depth rating, reportedly to appeal to the expanding US market.