Helmetlok Carabiner Style Helmet Lock and Extension (,) HelmetLok is a Carabiner-style lock, with a 4 digit programmable locking mechanism, designed to lock your helmet to your bike, while compact enough to fit in your pocket or on your belt loop Open the lock, slip the Carabiner through your helmet's shackle, attach it to your bike and lock it, since it's not permanently mounted, you are free to attach your helmet to anywhere on your bike The locking arm pivots outwards when open, allowing you to attach it to large diameter handlebars, bike frames, gear racks and grab rails, or around anything with a 1.5" max diameter The 4 digit locking mechanism is made from weather resistant zinc alloy and to protect your bike, and the aluminum Carabiner is covered with a protective plastic coating Includes the Helmetlok T Bar Extension for helmets utilizing a quick release style buckle, or when you need an extension for a D ring helmet, helping you enjoy the security and freedom of Helmetlok