This bi-metal holesaw set from Universal is suitable for wood, plastic, plasterboard, aluminium and thin mild steel Universal Bi-Metal Holesaw Set comes with 6x holesaws (19mm ,22mm ,29mm ,38mm ,44mm and 57mm), arbor for 14-30mm holsaws, and arbor for 32-152mm holesaws High quality Bi-metal holesaw set, with the most common sizes for electrical projects Holesaw Set has strong M3 steel teeth for sharper cutting in various materials Slotted barrel for effective material removal from inside