The Blaylock Gooseneck Trailer Coupler Locks are known for their reliability and easy use, they are also a target for thieves when left unattended. Specifications•Compatibility: 2-5/16 Inch Gooseneck Couplers•Pin Size: 3/4 Inch•Material: Aluminum•With Padlock: No Solid Hardened Steel Lock Rod For Security Crafted With High Grade Aircraft Aluminum. Rust-Proof The Best Theft Deterrence Device Designed Specifically For Gooseneck Style Couplers | Blaylock Gooseneck Trailer Coupler Lock, 3/4 inch Pin