Eaton Bussmann series of MOVGTs are radial leaded overvoltage protection devices that feature an integrated Metal Oxide Varistor (MOV) and Gas Discharge Tube (GDT) in series as a drop-in replacement to basic radial MOVs. They are available in disc sizes from 7 mm up to 20 mm and MCOV values from 70 to 600 V, suitable for Vac circuit voltages from 50 to 480 Vrms. The MOV & GDT combination provides higher surge current withstand and longer life vs traditional MOVs. This is accomplished by coordinating and arranging the MOV and GDT voltages such that the GDT isolated the MOV from small transients that are negligible to the overall system but can unnecessarily age the MOV. However, when subjected to large transients, the GDT activates and the MOV properly clamps the damaging voltage, providing the necessary protection.