metalab curb bit with hollow mouthpieceCurved and hollow mouthpiece for even pressure distribution on the horse's tongue and reduced palate pressure The long shanks create a stronger action The curb chain adjustment changes the severity of the bit it should lie flat, in contact, and allow a 45 angle between the shanks and the line of the mouth The use of a curb chain guard is recommended to protect the sensitive bone of the lower jaw This bit is recommended for experienced riders