The Most Compact Of The STX Series Offering, The Surge-Trap® Type 1 STXH Meets Requirements For UL1449 Fourth Edition and Is Suitable For Any 120/240VAC Split Phase Application. The STXH Series SPD Features Tpmov® Technology Inside Making It The Safest Product Available In Its Category. Its Compact Size, Performance and Reliability Is Especially For Hvac Applications and Direct Mounting to Air Condition Disconnect Switches., 240/120V, L-N, L-G, Split Phase, Led 50 Ka Per Phase