Magnetize any screw driver blade by simply leading the tool though left opening. Excellent for picking up tiny steel eye glass screws. Demagnetize by leading the blade through the right side, useful when you want to BE SURE the tool is demegnetized, such as when working inside a computer! Powerful rare earth magnets produce instant results. Excellent for opticians. Optional Optician's screw driver with replaceable double ended slot tip and finger cushion for eyeglass repair.