Kimblewick with Comfort Bar - this bit is literally a D-ring with a short, straight purchase at the top of the D but functions as both a direct action and leverage but using a curb strap. It the rein is attached to the top hook it will work as a direct action bit, exerting the same amount of pressure on the mouth as used on the reins. If the rein is attached to the bottom hook it will work as a leverage bit, tilting the mouthpiece forward and therefore applying pressure to the parts of the mouth curb and poll.
The comfort straight bar or Mullen mouthpiece is a very mild mouthpiece as it is unvarying which means the pressure on the mouth doesn't change much as it's a fixed mouthpiece. It's a very useful type of mouthpiece for horses who have a very soft mouth and don't like complicated mouthpieces.
Available in Soft or Hard in sizes 100mm-140mm