With Rolex period blank Guarantee, The Submariner brochure, Rolex Oyster Guaranteed 100 meters/330 ft. under water anchor and presentation box.
The anchors were attached to every Submariner to signify that the model was pressure-proof to the indicated depth.
Reference 6536/1, successor of reference 6536, was introduced in 1955 and remained in production until 1959. Essentially identical to its predecessor it was also available with the chronometer version of calibre 1030. It also featured a case without crown guard and a 6 mm. crown with the small line below the Rolex logo. The black laquer dials show the white printed depth rating “100m=330ft", gilt printed "Submariner" and gilt Mercedes hands. The bezel of early models had minute markers in 10-minute intervals and a red triangle, later series the minute markers for the first 15 minutes.