Omega gents seamaster planet ocean big size watchsteel on steelchronometerdatehelium escape valvescrew in crowntransparent case backunidirectional rotating bezelcrystal domed scratch resistant sapphire crystal with anti reflective treatment on both sidescase steeldial blackwater resistance 600 m 2000 feetsize case diameter 455 mmmovement caliber omega 8500 self winding movement with co axial escapement for greater precision stability and durability free sprung balance 2 barr