Kimberwick bits

A bit featuring a curb strap, D rings and shanks.  Because of the shanks, they are typically regarded as a curb bit.  Curb action is mild because of the short arms and no lever.  They are not widely used as snaffles and pelhams, and are even illegal in some competition classes, such as dressage and hunter jumper.  Considered non-classic and are avoided because they may cause the horse to over-flex or learn to lean on the bit, but can be stronger than the snaffle and used on stronger horses.  Typically seen on ponies.

Sources:

Wikipedia

bigdweb.com