To limit grab-and-run theft, just unlock the hinged clasp, hang your helmet by its strap and relock with the included key. Your helmet is held securely in place. In addition, hanging your helmet reduces the risk of impact damage if the helmet slipped off the seat or the handlebar. Designed to be installed to .875" to 1.25" diameter tubing engine guards, saddlebag guards and frame tubes, the Helmet Lock is secured to the bike with tamper-proof hardware that cannot be easily removed. Note: Do not use lock when vehicle is in motion. Helmet Lock should only be used when motorcycle is parked and locked. Duplicate keys are not available.