Measuring a transformer with a standard multimeter will not give accurate results because it is measuring DC resistance, not AC. This invaluable unit has a whopping 30mm high, backlit display and is fantastic for checking transformers and speaker impedances. Applies a 30 second test tone signal upon activation of the “test” button. May also be locked in test mode for continuous tone. Supplied in a safety yellow plastic case to protect the unit when not in use. Requires 6 x AA batteries.