I figured I'd throw this out there, as I have been looking for a lock solution for both equipment trailers with lunette setups. I would usually park a truck diagonally infront of both lunette rings, to prevent someone from pulling in, and hooking up a trailer. Well, the one night I had the truck at the dealer, one of my trailers got yanked. I posted a thread a bit back, about GPS locators for equipment and trailers. At that time, I was contacted by a site sponser, Ken Gustafson of http://www.trailerlocksonline.com/ after seeing my thread. At the time, I had no idea he was a sponser, I throught he was someone that had the same problem as I did. A few PM's back and forth later, I realized he offered a product that was pretty much what I was looking for. Ofcourse I was skeptical, like anything else that I've thought about trying and never saw first hand before. After getting off the phone with my Insurance agent, wondering how much my policy rate will increase, I decided to order a lock, and give it a try. Well, I recieved it on Monday, and I have to say I'm very pleased with what I got. I sat there and tried to come up with a way I thought I could break it off if I was a theif, but couldn't. If anyone is looking for a cheap way to secure a trailer with a lunette ring, check out http://www.trailerlocksonline.com/ Ken is great to work with, and can answer any of your questions. And believe me, I had many. This isn't a paid advertisement, but I would highly recommend giving them atleast a look.