Details
Master Lock - (3) Keyed Alike Universal Trailer Coupler Locks 379KA-3

This is a set of 3 Keyed Alike trailer coupler/tongue locks and is ideal when needing multiple locks that utilize ONLY one key. The same key opens all three locks. Each lock comes with two keys, therefore you will receive a total of six keys with the purchase of this 3 pack. Limited Lifetime warranty.
These locks protects unattended trailers and guards against tow-away theft. The universal trailer coupler lock fits 1-7/8in (48mm), 2in (51mm) and most 2-5/16in (59mm) couplers by Reese, Fulton, Valley, Atwood, Shelby, Putnam, Hammerblow, Dutton, Lainson, and UFP.
This simple design is difficult to defeat because when it's locked on the trailer the lock rests on top of the coupler (see image) thus thwarting blunt force from downward hammer strikes. It also rotates (less rigidity) making it harder to break with sledge hammer force.
Rekeyable cylinder for keyed alike convenience with an advanced locking mechanism that resists picking and prying. Each lock weighs 2.4 lbs. and is simple to install and remove.
Made with Reinforced Zinc Die-Cast resists rust and corrosion. Few materials provide the strength and toughness of zinc alloys. Impact resistance is significantly higher than cast aluminium alloys, plastics, and grey cast iron. Zinc alloys offer high strengths (to 60,000 psi) and superior elongation for strong designs and formability for bending, crimping and riveting operations.