Harmony Plug in Relays is a complete range of general purpose industrial relays, sockets and accessories. Harmony plug in relays optimize design flexibility, expedite installation and simplify maintenance with 8 to 30 A load ratings, multiple contact combinations, a wide range of coil voltages, and full feature covers. The Harmony plug in relays have a test button which allows users to check circuits for proper operation. They have lock down door holds contacts in place to test circuits during maintenance. A standard mechanical flag indicates relay status. An optional bipolar LED indicates operation when relay is energized. Most of these relays plug into a relay socket that can be DIN rail mounted or panel mounted. Harmony plug in relays are UL Listed. """"