Diamond Fire & Smoke actuators are designed to meet both UL-555 and UL-555S safety requirements at 250?F for fire and smoke applications. Diamond Fire and smoke actuators are not designed for HVAC applications and HVAC actuators are not designed for fire and smoke applications. Diamond Fire and smoke actuators are fast acting and have a faster spring return and close-off than HVAC actuators helping to prevent the spread of fire and smoke. Simplified shaft adapter, 360? swivel and clip-in conduit connectors, and small form factor means Diamond actuators easily accommodate most length, width and depth restrictions. Material savings from 360? conduit angles reduces the amount of conduit needed for installations.