The Boyle Davis mouth gag with Tonsil plates,adult 5 blades.This instrument is part of the tonsillectomy set. Mouth gags are used to keep the patient’s mouth open during oral surgery, leaving both hands of the surgeon free to operate. The Boyle Davis mouth gag consists of the Davis gag, a frame that serves to hold the mouth open and the Boyle tongue depressor to hold the tongue down. The tongue depressor comes in several sizes, from pediatric to adult. The instrument is assembled by sliding the tongue blade into the frame.