The most compact of the STX series offering, the Surge-Trap® Type 1 STXH meets requirements for UL1449 4th 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 are especially ideal for HVAC applications and direct mounting to air condition disconnect switches.