A power drill is needed to drill a hole in the cortical bone to allow screw insertion. Air-powered, electrical, and battery-powered drills are available. The drill must be properly sterilized using steam or gas, or it may be placed into a sterile shroud to prevent contamination of the surgical site. Drill bits, drill guides, cortical taps, a measuring device to determine the appropriate screw length, instruments to contour the plate to the bone surface, and a screw driver are also required. Many of these instruments are specific for the size of screw and plate being used.