I use them along with a 25 foot nylon rope (homemade) to tie my horses at the trailer. I have a small, extremely light aluminum stock trailer, and if one of my good-tying horses spooks and pulls, odds are that the little trailer's going over, even hooked up to the truck. I've never actually had a horse test them, but I do like them and imagine that they might be a good option for some true problem tie-ers as well as a safeguard for horses that do tie well. One of the few "gimmicky" gadgets that I would highly recommend without reservation.
A stubborn horse walks behind you, an impatient one in front of you, but a noble companion walks beside you ~ Unknown