Glad Hand Lock Keyed Alike 10 Pack Heavy Duty Aluminum Air Brake Glad Hand Lock for Tractor TrailerPack Size: 10 Pack Color: Red, Cast Aluminum Glad Hand Locks. Included in your order is the following: Cast Aluminum Gladhand lock with 2 keys each. (NOTE: 10 Locks and 20 keys are on the order). Glad hand lock is the perfect device to "dead line" a trailer, offering a simple way to prevent a trailer from being moved while being loaded or unloaded. This semi trailer lockout device acts as a harness around the air intake valve of the emergency brak.