(4) pieces Registers: Control & SAVE on energy bills with our Exclusive Precision Airflow Regulator Mechanism. Infinitely adjustable louver assembly (damper box) let’s you control every room’s airflow while saving you money. Made of rustproof cast aluminum & treated with a baked-on powder coating for a luxurious black finish, each register is adorned with a Renovator’s Supply logo. Not recommended for walls or ceilings as the damper box does not lock in place. Measures 9 3/4 in. diameter.