These amazing little key rings are super strong, super high quality, and are what we've been using as components in Specialist ID Products for years! The benefits of heat treated steel are increased strength, hardness, toughness, and wear resistance. Making them much harder to bend or break. This process basically alters the micro-structure of the steel by exposing the steel to high temperature for a certain period and then quenching it (rapidly cool). The product is nickel plated after the treatment.