check out http://www.shop4bits.com/item--The-Team-Up-Bit-12mm-DL-55mm-Bradoon-Rings--9012.html
http://www.shop4bits.com/item--NS-Tranz-Loose-Ring-Pony-10mm-DL--8093.html
If you horse doesn't like bits, then just plain don't go there. Especially if you're asking for a single jointed one.

Average, for horses with some experience at this level