I'm hopelessly amused by the picture and copy on this bondage-gear website. For high-protocol training and/or high-speed impacts! I have this great idea for a scene where I put the collar on her and then I strap her whole body to a board and tie her wrists together and tape her head down...
(I'm not entirely sure you can "train" someone's collar height, that has a lot more to do with bone structure than obedience, but whatever floats your crazyboat, I guess.)
I notice they've adjusted the pricing to reflect the BDSM market, too. I can save you fifteen bucks.
P.S.: Dang, I might need to order these, I didn't realize they were so cheap. Even the good ones are downright reasonable.