Kryptonite Keeper U-Lock The Kryptonite Keeper U-Lock is made of twelve centimeters thick hardened steel and has a protective vinyl coating. It is resistant to hand tools, so your bike is almost impossible to steal. It has a reinforced collar for extra protection. The secure Bent Foot design and the Key Safe program ensure great ease of use and a sturdy design. Specifications: Color: black Gender: unisex Material: steel Material coating: vinyl Weight: 1.27 kg Shackle thickness: 12 mm Length: 29.2 x 10.2 cm (L x W)