Stainless steel 316L (Stainless Steel) is a very durable material that theoretically can not be destroyed. It is hard (non-bendable and non-crackable), color stable, antiallergic (does not react with body fluids and therefore no metal components are not released into the skin and flesh) and has anticorrosive surface (the surface is resistant to oxidation and corrosion. Moreover, it is also resistant to fresh and salt water).

Watches marked with water tightness 100M/10ATM are designed for swimming and snorkeling and free diving without breathing apparatus. 100M/10ATM indicates the degree of water resistance standardized by ISO 6425. ISO tests include temperature changes, depth, pressure (water and air) for different times under the  rest and during manipulation with the operative part of the watch.

Currently the most widespread type of watch glass. It's very hard and has a high content of silicon thanks to which it's  highly scratch- and impact-resistant. However, it doesn't mean that it is completely scratch-resistant.