The mastercheck voltage tester has an led scale for indicating all voltages in the domestic environment the mastercheck 2mm is a 2 pole voltage tester that is also capable of indicating polarity and continuity a 2 pole voltage tester is the only approved testing instruments that fulfils the requirements of work protection regulations voltages of 50 volt ac or 120 volt dc and over can be tested without a battery other features include one handed operation and automatic battery monitoring tested a