cannulated, 3 jaw stainless steel chuck, accepts wires & pins up to 5/32″ (4.0 mm), aluminum body Bunnell Drill is a specialized instrument used for drilling through bone in neurosurgical and orthopedic procedures. This instrument is cannulated and features stainless steel chuck. This drill is uniquely designed with a hollow design that allow for wires and pins to pass through it up to a diameter of 4.0 cm. Additionally this drill is designed with an aluminum body and comes in a design that features a chuck key.