Master Lock - Gooseneck Coupler Trailer Locks 2989KA Fits both Fixed and Adjustable style Gooseneck /Fifth Wheel Style Trailer Couplers. Fits 3" Lunette Rings and King Pin If you order multiples of this lock, they will NOT be keyed alike. Laminated steel frame construction for reliable performance. Powder Coated finish resists corrosion. Re-keyable Python Cylinder. Keyway cover protects lock from moisture and dirt. Easy to install and remove.