12" x 12" [Duct Opening] Ceiling Supply Diffuser Vent Cover – 1-Way Airflow with Full Aluminum Frame, Back Blades & Opposing Blade Lever Damper [Outer Size: 15" x 15"] Grille prime the pump according to

prime the pump according to the manual instructions to remove any air trapped in the system

actual front end outer dimensions are approximately 36 5/8" width X 30 5/8" height

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For 12" duct opening

12" x 12" [Duct Opening] Ceiling Supply Diffuser Vent Cover – 1-Way Airflow with Full Aluminum Frame, Back Blades & Opposing Blade Lever Damper [Outer Size: 15" x 15"] Grille prime the pump according to+ Product Details Size Refers to duct opening only. The face frame extends roughly 1. 5" on each side. Do not measure the overall grille for sizing. Design All aluminum frame and back blades. Rustproof and built to last in moisture prone environments. Quiet Airflow Opposing blade damper design reduces vibration and noise for smoother air distribution. Clean Finish White powder coated surface resists chips, scratches, and discoloration over time. Easy