Clear Plastic Regal Thermostat Cover - Ring & Solid Bases - 6-3/8" x 3-1/2" w8h8 + Product Details Size –

+ Product Details Size – 8"w X 12"h is the size for the duct opening measurement only

Think of the diameter as a straight line from one end to the other

Optional Butterfly Damper Available At Asin: B007CNEL1W

+ Product Details Size – 22"w X 34"h is the size for the duct opening measurement only

For enhanced airflow control

Clear Plastic Regal Thermostat Cover - Ring & Solid Bases - 6-3/8" x 3-1/2" w8h8 + Product Details Size –+ Product Details Durable Construction Made with clear, high impact plastic to provide reliable and long lasting protection for your thermostat. Two Mounting Base Options Includes both a solid base and a ring base. The ring base allows installation without removing the thermostat, offering maximum flexibility. Locking Security System Features a built in eight tumbler lock and a supplied key to prevent tampering and maintain consistent temperature