With Rolex original presentation box and outer packaging.
The present Rolex Sea-Dweller reference 1665 is an extremely rare example, featuring several special features. Firstly, it has what collectors refer to as a Mark I dial, secondly, it has the rare engraving on the back "Oyster Gas Escape Valve (Patent Pending)", and thirdly it comes with a prototype Rolex bracelet and clasp.
The present dial is very charismatic in the way that it has aged, the black matte dial with light gray speckles throughout and the Double Red writing faded to almost white. The Double Red Sea-Dweller writing is divided into four different types of dials, Mark I through Mark IV, with the first one, as seen on this watch, being the rarest dial. The Mark I dial for Double Red writing has both the words "Sea-Dweller" and "Submariner 2000" written in the same size, and on many watches has faded over time from red to pink, and becoming almost white. The Mark I dial can also be characterized by having the "S" of Sea-Dweller paced in perfect alignment with the "B" of Submariner 2000.
The case back has the much sought-after engraving on the back, reading "Oyster Gas Escape Valve (Patent Pending). The helium valve, which allows helium and other gases to escape, thus enabling the watch to withstand compression at extreme depths, was developed by Rolex with the French diving firm Comex and first used for Submariner reference 5513 and 5514. With the success of these models, Rolex decided to commercialize their invention with the launch of the celebrated Sea-Dweller reference 1665 in 1967. It was the first wristwatch designed for use in saturation diving, fitted with a Rolex patent valve in the band, and guaranteed waterproof to 610 meters depth. The model was put into production while Rolex had not yet received the final approval for the patent of the helium valve, which resulted in the first models of the reference 1665 being sold with the case backs engraved "Patent Pending" in parenthesis.
Furthermore, the inside of the case back has the correct reference number 1665, the last three digits of the serial number, and the quarter and year of production - IV.67. The watch also has a rare prototype Rolex bracelet with the company's iconic crown on the edge of the deployant clasp, and with an extension piece marked Rolex .
The combination of all of these elements makes the present watch a "must have" for any Rolex aficionado.
A similar Sea-Dweller Submariner with "Patent Pending" is illustrated in 100 Superlative Rolex Watches by John Goldberger, p. 190.