McGard outboard lower unit lock bolt is designed specifically for Yamaha lower units and features a stainless steel locking bolt. Simply replace one of the Original Equipment bolts above the propeller with a McGard lock bolt. Once installed our lower unit lock bolt offers 24 hour protection. Constructed of through-hardened stainless steel for maximum security. A free-spinning collar will turn if attacked by gripping tools without loosening the lock. For maximum security, use the Yamaha lower unit lock bolt in conjunction with a McGard outboard motor lock to avoid costly theft.