From: Horse Bits

See also: Horse TackSnafflePelham

Horse Picture

Gag Bit
The gag bit offers the same action as a snaffle bit with the addition of leverage pressure, what sets it apart from the pelham bit is that it is not used with a curb chain.

The amount of leverage and severity of the bit will depend upon the type and length of gag shanks and the mouthpiece chosen, and as with any bit the severity ultimately comes down to the riders hands.

Gag Bit Points Of Pressure
Gag bits have a lifting effect due to the leverage pressure and are well suited to strong horses prone to lowering their heads.

Gag Sizes
Gag bits are measured from between the mouthpiece rings or shanks and are usually available in sizes ranging from 3, 3.5, 4, 4 1/4, 4.5, 4 3/4, 5, 5 1/4 , 5.5, 5 3/4 and 6 inches.

Gag Mouthpieces
Gag bits have several mouthpiece options available. As a guide thin or twisted mouthpieces are far more severe than straight bar wider mouthpieces which spread the pressure more evenly across the tongue, however each horse is different so you'll need to think carefully about what is going to be most comfortable for your horse as what works for one horse may be far from suitable for another.

Gag Shanks
As a rough guide the longer the gag shanks and larger the snaffle rings are the more leverage pressure will be obtained:

Materials Gaga Are Made Of