Read more SAPPHIRE CRYSTAL This watch has mounted sapphire crystal, which is the strongest and most resistant glass a watch can have. 316L STEEL The watch is made of 316L surgical stainless steel, which is considered to be the best quality of steel for the production of watches. WATERPROFF The watch is waterproof to 100 meters (10 ATM). This means that it can be used for all kinds of water activities - including tank diving. Read more