Clear Plastic Thermostat Guard - See Thru - Solid Base - 8.25" x 5.37" - Extra Large - With Lock & Key Material_Aluminum + Product Details Size -

+ Product Details Size - 26"w X 12"h is the size for the duct opening measurement only

actual front end outer dimensions are 16" width X 8" height

+ Product Details Size - 28"w X 8"h is the size for the duct opening measurement only

actual front end outer dimensions are approximately 14 5/8" width X 28 5/8" height

Clear Plastic Thermostat Guard - See Thru - Solid Base - 8.25" x 5.37" - Extra Large - With Lock & Key Material_Aluminum + Product Details Size -+ Product Details Universal Fit Accommodates almost any thermostat with dimensions of 8 1 4" H x 5 3 8" W x 3 1 2" D. Durable Construction Made from high quality, high impact clear plastic for long lasting performance. Locking Security System Features a built in eight tumbler lock and a supplied key to prevent tampering and maintain consistent temperature settings. Easy Installation Comes with all necessary installation screws for a quick and hassle