Uni Air Filter BF-5 Foam Sheet - 230-37 Uni Filter Replacement Red Mesh Course Foam Air Filter - Sheet Size 12 X 16 X 3/8 - 40 PPI Red Coarse Foam. Please see our Warranty & Returns Policy. Item Number: BF-5 Foam Piece: 16" x 12" and is 3/8 Inch Thick 40 PPI (pores per inch) Easy To Use: Place your existing filter on top of foam, trace it out, and then cut it out with scissors Made in U.S.A.