Generally, it will have the addition of a leather jowl or jaw strap that attaches above the mouthpiece and passes around the jaw. This is well above the chin groove that a curb chain would sit in, over an especially sensitive part of the lower jaw.

A bit for employment by only the experienced and skilled rider, it is used on horses that respond to contact being affected initially outside of the mouth. It is also useful for those who may be more prone to damage upon their lips from the likes of a Running Gag.