Wireless Green Zone Control dampers are now available from Alan Manufacturing Inc. Pictured is a retrofit model. The dampers are available in round 4 inch to 24 inch and equivalent rectangular. The unique gasket moves with the blade. Any thermostat can control the motor, which uses no springs. The warranty is three years.
 
3927 E. Lincoln Way, Wooster, OH 44691; Canada; (800) 435-2526; www.alanmfg.com