Collectors call this watch the "Single Red" Sea-Dweller due to the fact that the "Sea-Dweller" name is printed in red. In contrast, the "Double Red" Sea-Dwellers have both "Sea-Dweller" and "Submariner 2000" printed in red letters. Underneath the red "Sea-Dweller" text on the "Single Red" is "Submariner 500 M - 1650 FT". Beneath that you read "Superlative Chronometer" and then "Officially Certified". The top of the dial has the Rolex coronet, "ROLEX" and "Oyster Perpetual DATE". The watch is a case reference 1665 with the outside of the caseback stamped "Oyster Gas Escape Valve" and "(Patent Pending)" around the outer rim. The inside caseback is stamped "1665" and "IV 67", the first year the "Sea-Dweller" was produced.