Amplock is a highly rated trailer coupler lock. After having a trailer stolen, I’ve come to trust these super duty units. I’ve used a bunch of different types. Wheel chocks, chains, cheap coupler locks and none stack up to these! They use a two code cuts in the keys, making them near impossible to pick and duplicate. You must have both numbers to get duplicates/spares and you can register with Amplock, your codes, so they have them on record and can get you keys if they become lost.These locks are not cheap, but I feel they are worth every penny. Keeping folks from taking your trailer. Check these out, then come get one from me. Please look at the photos to make sure these will work for you. These sell for $265 new. I have three new: 1- BP2 for 2” ball and two BP2516 for a 2 5/16 balls. $150 each, firm!