Description

From 1 to 600 Rd  Square Inches ,ONLY

Using the proper calculation will determine the size of your filter…

PLEASE NOTE: Fractions are rounded up to the next square inch when calculating Total square inches. 

 (Example: 18″ x 20-1/4″ = 378 total ROUND square inches.) 

Please measure outside frame to the outside of the frame as shown.

Turn the filter on it’s side to measure the frame thickness.