Rolex 126503 bkio 40mm yellow Rolesor case comprised of Oystersteel and yellow gold, screw-down back, screw-down crown with triplock triple waterproofness system, fixed bezel with engraved tachymetric scale in 18K yellow gold, scratch-resistant sapphire crystal scratch-resistant sapphire, bright black dial, index hour markers , diamond hour markers, 4131, manufacture Rolex perpetual, mechanical chronograph, self-winding movement with centre hour and minute hands, small seconds hand at 6 o'clock, chronograph via centre seconds hand, 30-minute counter at 3 o'clock and 12-hour counter at 9 o'clock, stop seconds for exact time setting, approximately 72 hours of power reserve, Oyster bracelet with three-piece solid links, folding Oysterlock safety buckle with Easylink 5mm comfort extension link.