Omega Speedmaster '57 Co-Axial Chronograph Watch - 41.5 mm Steel And Yellow Gold Case - Silver Dial - Steel Bracelet - 331.20.42.51.02.00141. 5 mm stainless steel and yellow gold case, transparent back, 18K yellow gold bezel with tachymeter scale, scratch resistant sapphire crystal with anti reflective treatment on both sides, silver dial with a seconds sub dial at 9 oclock and a 12 hour and 60 minute chronograph recorder on the sub dial at 3 oclock, calibre 9300 self winding movement with a central chronograph seconds hand and a date window at 6 oclock, approximately 60 hours of power