ZoneFirst AOBD-20X10 Damper 320788-703 What is the difference between

What is the difference between the silver and other color-coded Spence springs

Maintenance-Free: Factory calibrated with a platinum PTC sensing element that maintains accuracy over time without manual adjustments

the sensor wire is likely the failure point

This unit is built for continuous air-over (DAO) operation

ZoneFirst AOBD-20X10 Damper 320788-703 What is the difference betweenThe ZoneFirst AOBD 20X10 Damper is a professional grade automatic opposed blade damper engineered for precision bypass and zone control in high demand residential and commercial ductwork. This 20" wide by 10" high unit features an anodized extruded aluminum frame and blades, ensuring a low profile footprint that fits into 3 inch slots for streamlined side mount installation. Each blade is connected via a stainless steel draw bar and nickel plated