The Kryptonite keeper 585 folding combo lock features 3mm hardened steel links. Rated at a 5/ 10 on our security scale, The Keeper 585 is good for quick stops in a metropolitan area, a couple hours in the suburbs or all day & overnight in rural areas. It also includes an easy-to-install transport bracket providing convenient multi-location lock transport. The combination of these great features and our support programs including combo safe, Anti-theft protection, and lifetime make Kryptonite bicycle locks the best choice for protecting what you value.