Full cheek snaffles may have a plain jointed mouthpiece or a variation like copper rollers. The copper rollers help increase sensitivity by promoting saliva flow in the horse’s mouth. Long cheek pieces prevent the bit from pulling through the horse’s mouth. The bit can be used with keepers that attach to the bridle and keep the cheeks more or less vertical. The mechanism of the bit is similar to other jointed English snaffles in that the mouthpiece puts pressure on the bars of the mouth, and if jointed the tongue and roof of the mouth. Using the keeper to keep the cheek pieces vertical also acts to exert a slight downward pressure on the crown of the bridle. This is a very commonly used English snaffle bit for schooling and general riding.