Ratio FreeDiver Black Dial Sapphire Crystal Stainless Steel Automatic RTB200 200M Men's Watch The Ratio FreeDiver Black Dial Sapphire Crystal Stainless Steel Automatic RTB200 200M Men's Watch is all about heavy-gauge surgical steel that doesn’t turn the watch heavy yet turns it heavy duty. Its construction (case, screw-down crown, engraved case-back w/image of a free diver and the deployment clasp) gives it the weight. It pleasantly assures its presence with its heft while increasing the momentum of your hand’s movements, rather than tying you down with its weight. The thick gauge, surgical-grade stainless steel and the sapphire crystal offers high resistance against damaging water pressure (equivalent to pressure exerted by a 200m high water column on the watch’s surface area), physical impacts (including violent tugs) and magnetic resistance to handle magnetic fields from electronic and electrical equipment we come across in daily life.The crystal, the case and the Freediver-etched case back together protect the Japanese mechanical movement (with its own shock/antimagnetic features) together against violent knocks, bumps and drops. Specs and their implications Water Resistance Water resistant up to 660 ft.Suitable for professional and everyday use.Suitable for Skin Diving, Scuba Diving, Deep diving, Swimming, Snorkeling, Surfing; spear-fishing. Luminescence Ratio uses Japanese luminescent paint for the luminescence in the Freediver 200m watch. It is a non-radioactive, radiant paint that's applied generously on the hands and the indices of the Freediver. The paint exhibits greater intensity and longer-lasting luminescence. Japanese Automatic Movement Caliber: NH35AJewels: 24Accuracy: +20 seconds/dayShock protection System: Diashock Prime points Generous use of solid, surgical-grade Stainless Steel CaseJapanese Automatic Movement with Caliber: NH35AVisually appealing watch face with uniquely shaped hands.Black DialSapphire crystalUnidirectional Rotating Black Bezel With 120 ClicksBezel With Ceramic Inlay200m water-resistanceApproximate Case Diameter With Crown: 46mm