21x27x5 Trane Perfect Fit BAYFTFR21M Aftermarket Furnace Filter / Air Filter - AFB Silver (Merv 8). (2 Pack) 21x27x5 Trane Perfect Fit BAYFTFR21M Furnace Filter / Air Filter - AFB Silver (Merv 8). (2 Pack) Specifically designed by AFB to replace Trane Perfect Fit BAYFTFR21M filters Removes lint & dust, dust mite debris Pack of 2 Filters Merv Rating of 8