Kyoritsu 8031 phase indicator with open phase checker. Designed to check the presence of open phase and also the phase sequence by rotating disk and lamps. Can check a wide range of 3-phase power source from 110V to 600V. Operational voltage: 110-600 VAC. Time limit for continuous: >500V, within 5 minutes. Frequency response: 50/60Hz. Withstand voltage: 5550V AC for 1 minute. Accessories included: 9029 (carrying case), instruction manual. Measures 106mm length by 75mm width by 40mm.