Round dampers are power open/power close. 24 vac actuator has red and green LED’s that indicate when damper is fully open and fully closed Screw terminals are reliable and easy to use. Each motor allows adjustment of the minimum close position. The gasketed edge on the blade furnishes a 99% shut off. The ½” shaft is made of solid aluminum for long lasting strength and reliability. Two bolts with neoprene nuts attach the damper blade to the ½” shaft to insure reliable operation.