MODEL: 16600 S/NO: "Y821xxx" SERIES YEAR (2003-04). Chronometer in stainless steel case 40mm, original Rolex stainless steel flip lock oyster bracelet. Graduated rotatable bezel. The special oyster case with gas escape valve for saturation diving & with shoulders to protect the trip lock winding-crown. Waterproof to 4000 feet. Automatic movement. With pinhole. (Discontinued model, highly collectable.)