Clear Plastic Regal Thermostat Cover - Ring & Solid Bases - 6-3/8" x 3-1/2" w8h8 Actual Filter Size – 33

Actual Filter Size – 33 3/4"w x 17 3/4" x 1"

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

Optional Butterfly Damper Available At Asin: B007CNEL1W

actual front end outer dimensions are approximately 38 5/8" width X 16 5/8" height -

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

Clear Plastic Regal Thermostat Cover - Ring & Solid Bases - 6-3/8" x 3-1/2" w8h8 Actual Filter Size – 33+ 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