Polished stainless steel case. Polished 18kt yellow gold fixed bezel ring with engraved & black filled Tachymeter scale. Polished 18kt yellow gold screw-down crown with Rolex's patented 'Triplock' triple waterproofness system, ensuring that the crown screws down against the Oyster case as securely as a submarine hatch. Screw-down chrono buttons in polished 18kt yellow gold. Dial: Black dial. Black sub-dials with fine yellow gold rims. 8 diamond hour markers. Fine printed minute/seconds & fractions of a second track. Polished yellow gold hands - hour & minute hands with black center line & partial luminous fill. Chronograph/Stop watch function: Large central seconds counter hand, accurate up to 1/8th of a second. 30 minute counter sub-dial located at the 3 o'clock position. 12 hour counter sub-dial located at the 9 o'clock position. Continuous running small seconds hand sub-dial located at the 6 o'clock position. Rolex in-house calibre 4130, beats at 28,800 vph, contains 44 Jewels & has an approximate power reserve of 72 running the time only or 66 hours with the chronograph function running. AKA: m116503-0008