Voltcraft ms 420 tester contactless voltage tester voltcraft ms 420 p the voltcraft ms 420 detects stationary electrostatic fields generated by ac voltage via the insulation without the need of direct contact to the plain conductor a red light at the tip of the device and vibration are signalling the presence of voltage in addition a led light is integrated to illuminate dark corners the device is powered with 2x aaa batteries p voltcraft ms 420 voltage tester cat iii 1000v