1 x PP3 battery. Non-Contact Voltage Indicator Martindale TEK100. A non-contact, 100 V ac to 600 V ac voltage indicator with both audible and visual voltage warning. A self-test feature (which ensures the unit is working) transmits a 50 Hz signal to the sensing device testing the integrity of the internal circuitry. Proving the unit is fully functional and avoids the need for a separate proving unit. Pocket-sized unit Voltage detection without making contact 100 V ac 600 V ac range LED light indicators Audible indicator Self-test function means there is no need to use proving units Replacement PP3 batteries can be purchased separately (Stock No. < 394-9059)') 394-9059)/ CAT IV 600 V