Gag bits often used on horses that are heavy on the front end or have a deep head set (head too near the ground). When rein pressure is applied, the bit slides upward and rotates slightly in the mouth. It can help in controlling an excited horse or one that tends to run off. Gags are often used with two sets of reins. One set attached to the cheek piece which engages the gag action, the other set it attached to the bit ring giving a snaffle action. The larger the bit ring the more severe the gag action. Rolled leather cheeks are more attractive, but not as fast in their action as rope cheeks that slide through the rings quicker, giving a faster and more clearly defined cue. Cheltenham gags have Eggbutt design rings. Balding gags have a loose ring design. Nelson gags have a full cheek design. 

Continental (3-4 ring) & Half Wonder Gags are similar to elevator bits, except the cheek pieces consist of stacked rings. Ring above the mouthpiece is used to attach cheek piece. The ring that is attached straight to the mouthpiece, acts similar to a snaffle. The lower ring(s), is for a second rein to be attached, which provides the gag action. The lower second rein is placed on the stack, increasing the gag action (raising of the mouthpiece up along the cheek piece) applied. These types of gags provide options for the severity of the bit. 

American Gag Bits have the shape of an "H". The American Gag has more leverage (gag action) due to the straighter long shanks. It will assist to raise a head, turn and/or stop. This is considered a very loud bit, so it should be used carefully and by knowledgeable riders. There are some bits in the Western section that have minor gag action.