Pelham Bits
Pelham is a combination bit essentially combining the action of the double bridle into a single bit. Pelhams can be used with a double rein or a converter which would mediate the action between the snaffle and the curb rein to somewhere in the middle.
The curb strap can be a chain or a leather strap, which must be fitted so that shanks cannot move past 45 degrees upon engagement of the reins for correct bit action.
Often used in show jumping and equitation, pelhams are a great alternative to gag bits when the horse responds better to pressure on the chin groove over pressure on the poll and corners of the mouth.