Master King Pin Lock-Toy Hauler/Trailer Locks w/BumpStop #387NKA Secures the king pin of semi-trailers, RV's, and other fifth wheel trailers. Solid, cast aluminum alloy withstands physical attacks. Featuring the BumpStop technology. For explanation view SEE MORE PRODUCT DETAILS below. Lock, protected by the housing, resists common physical attacks: 1) Shackle cannot be cut. 2) Hardened steel bottom plate resists drill attacks. 3) Rivets are countersunk making chisel attempts fruitless Available Keyed Alike for your entire fleet.