Using cable operated dampers is the most convenient and economical way to balance air flow through the face of the diffuser, said officials from Duro Dyne. The control cable passes through the neck of the diffuser, and the damper position is changed by simply pushing or pulling on the cable. Once the adjustment has been made, the cable is locked by set screws.

Duro Dyne; 81 Spence St., Bay Shore, NY 11706; (631) 249-9000; www.durodyne.com/xephr/list/NEW_PRODUCTS .