"great training aid"
I got my first pair from Germany. I like the way the topline of the horse develops so fast and easy. Horse's nose should be in front of the vertical and the poll just above the withers. Horse learns to work from behind if the lunger/rider asks the horse to go forward and let the neck stretcher do its thing. I ride with it also. Not good for horses that avoid contact.
"Decent, but snap broke on first use"
I bought these to help get my horses working long and low off of pressure (poll & bit). They're decent (not too severe tension) but the snaps are cheap plastic. The adjustment tap (at the poll) also can easily be pulled against by the horse and the reins loosened, so they're not very effective in terms of securing certain degrees of tension. On first use, the plastic snap on one side broke with very little effort when the reins were at their loosest. This means I have to tie off both sides to get equal pressure or switch sides when I lunge. Not ideal. For $11, these are glorified bungee cords.