Clear Plastic Designer Thermostat Cover- Solid and Ring Bases - 7-1/16" W x 4-1/8" H x2 1/8"D Aluminum Bar + Product Details Size -

+ Product Details Size - The listed 6" diameter refers specifically to the size of the duct opening

excluding the old vent cover

actual front end outer dimensions are approximately 20 5/8" width X 20 5/8" height

and smooth surface

actual front end outer dimensions are approximately 24 5/8" width X 27 5/8" height

Clear Plastic Designer Thermostat Cover- Solid and Ring Bases - 7-1/16" W x 4-1/8" H x2 1/8"D Aluminum Bar + 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