Trammell Chain Mouth Bit w/ Gag
From the manufacturer:
These bits hang higher on your horse's head because the mouthpiece is at the bottom of the gag. To adjust--pull the mouthpiece up snug in the mouth the same as with any other bit. A noseband increases effectiveness. If you have a problem keeping your horse handling light and stopping good, this bit, when used correctly, will eliminate that problem.
5" chain mouth
9" cheek
2 1/2" purchase
2 1/2" gag
4" shank