Copper Mouth Tom Thumb Snaffle 5" Mouth 6" SS Cheeks. One of the most basic shanked type snaffle bits, the Tom Thumb Snaffle serves as an excellant transition bit from a Ring Snaffle to a longer shanked snaffle or to a Curb Bit. This bit uses a small amount of curb pressure or leverage. The loose cheeks move independently allowing for more lateral flexibility.