Premier Equine Copper Roller Dee BitWhy choose a roller mouth dee bit for your horse? The copper roller mouth dee bit is useful for horses that tend to fix or try and grab lean on the bit. The alternating copper and stainless steel rollers set along the mouthpiece enable the bit to move in the horse's mouth preventing them from grabbing or leaning on the bit. The single jointed mouthpiece has a nutcracker action applying pressure on the lips and bars of the mouth. The dee ring cheeks