Universal Trailer Coupler Lock for 1-7/8 inch, 2 inch and 2-5/16 inch Couplers - This maximum security trailer coupler lock will make sure that your trailer stays where you left it. Constructed from hardened steel and nickel plated to resist corrosion for years to come, this universal design protects most trailers from being towed away. The multistep uni-ball fits into any size ball coupler (1-7/8 inch, 2 inch and 2-5/16 inch) while the unique bend in the reversible shackle lets it snug up tight to most types of couplers or coupler latches, including A-frame, straight channel, round tongue, flat plate and surge-type couplers. Tube key lock cylinder provides better security than standard key mechanisms, is harder to pick and is more difficult to get duplicate keys for. The anti-drill pin discourages attempts to drill out the lock. 4 keys included. Bolt-blocked locking system prevents thieves from prying the lock open and uses internal bolts to engage the shackle's notches. Dimensions: (Shackle) 5/8 inch diameter and (Maximum Coupler Width) 4-1/2 inch. Limited Lifetime Warranty.