Bit gag
From wipipedia.org
A bit gag is based on a horse bit and is often used in pony play.
As a tool for silencing someone, it is much less effective than many other types of gag. However, the visual impact is as great as (some might say greater than) a ball gag and it is of course ideal for pony play. The risks of wearing a bit gag are much less than a ball gag since it does not obstruct the airway. Bit gags can be fixed in place either by a single strap running behind the back of the head or as part of a head harness. The bit can be made from a variety of materials; rubber, wood, and metal are popular choices.
Bit gags are also valuable tools for humiliation and ego reduction exercises, since they tend to cause the wearer to drool freely.
