This easy-to-wire damper includes a 24-volt motor used to control circulating air in HVAC systems. The ZD is a power close and spring open damper used when a normally-open damper is required. It's typically used with TrueZONE® and other electronic zoning systems. Kevlar gearing reduces wear, more than doubling damper life. Mechanical visual position indicator for damper status. Solid construction using extruded aluminum frame and blades. Parallel blade design for low leakage performance. Quieter operation with fewer blades. Reliable, strong, 24-volt spring-return motor. Fail-safe, normally open operation. Compatible with conventional and networked zoning.