Maker: Rolex
Model: Submariner
Reference number: 5512
Serial number: 1948666
Year: Circa 1968
Case size: Approx. 40 mm
Case material: Stainless steel
Bezel: Black
Dial: Black, 'meters first' depth rating
Movement: Automatic
Bracelet/Strap: 'Made in USA' stainless steel Oyster Rivet bracelet
Stamps: Case: 1948666. Case back interior: MONTRES ROLEX SA 5513 PATENTED STAINLESS STEEL IV68. Movement: TWENTY SIX 26 JEWELS 221347. Clasp: ROLEX USA 1-70.
Gross weight: 59.50 dwt.
Sold with: Rolex pouch

The Rolex Submariner Reference 5512 is a landmark vintage timepiece, produced from approximately 1959 to 1979. It is most notable for being the first Submariner to feature crown guards and a larger 40mm stainless steel case, establishing the iconic silhouette that modern Submariners still follow today. 
The "Meters First" designation refers to the depth rating printed on the dial as "200m = 660ft". 
These dials were produced from the late 1950s until approximately 1969, when Rolex switched to a "Feet First" format (660ft = 200m) to better appeal to the U.S. market.
Because they were in production for a shorter period and represent the earliest iterations of the reference, "Meters First" examples are generally more rare and more expensive than later "Feet First" models.