Serfas KL-PUCK Steel Plated Key Lock Security Rating system is based on lock thickness, locking mechanism, and force needed to cut our locks Hardened steel Ultra strong shackles Unique, self contained, hardened steel linked bicycle shackle lock Stainless steel rivets for extra protection Vinyl coated for durability and protects from scratching your bike Includes mounting bracket with quick release lock cradle Measures 10" in diameter when engaged (circle), 27" long (fully extended)