Demagnetizes or magnetizes parts or tools. Opening is large enough to accommodate cassette tapes for quick erasure. To demagnetize, simply hold object in the center of the opening with button depressed for 3 or 4 seconds. Slowly withdraw object in a straight line. Release button. To magnetize, hold the part of tool against the inside of the opening and press the button for 4 or 5 seconds and release. Measures: 3" X 1 1/2".