REPLACEMENT M847D DAMPER ACTUATOR MOTOR - 24Vac spring return damper actuator is designed to operate directly driven zone dampers, used to contol air fow in ducts. The synchronous motor acuator can be driven open (or chosed) using any 24 rated two position switch - eg.a wall swith or a thermostat subbase switch. The M847D replaces the RDMH andR damper actuators for use on TrolA-Temp@ ARD and ZD dampers. APPLICATIONS - 2-wire spring return damper actuator motor is compatible with for s M847D, M847D1004, and old ARD and ZD series of damper motors. DuroZone #35105 damper Motor & similar HVAC spring-return 2-wire damper actuators by Zone First, Erie, and others. Does not work with for ZD Rectangular Dampers. Please check the fitments before ordering! EASY INSTALLATION - Direct coupling to 5/16inch damper shaft. Can be used in either Normally Open (O.) HVAC air ducts, or Normally Closed (C.) venting installations. 2-Wire spring return actuator 24V is an ideal replacement for the model! Installation is pretty straight forward. Mounting Means: direct connection to damper shaft; Mounting Position: Multi-. ( TIPS: it is suggested to use the old for long set screw because it easier to tighten the set screw. ) Easy Installation: Motor as a upgrade Assist kit, Fits for most models, , perfectly fit, No Special Tools Required, just for a simple install.Colour:Silver Material:Stainless steelPackage Contents: 1 for Damper Actuator MotorOnly the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.