Merv 8 Pleated Air Filter - 18 1/4" x 21 1/2" x 2" Quantity:12-pack the more efficient a filter

the more efficient a filter is at removing particles

To find the size the old unit should have sizing information printed on it

Filtering inserts are shipped in an easily stored packet

PACK of 6 pads for Pad and Frame Air Filters

we even have the odd sizes

Merv 8 Pleated Air Filter - 18 1/4" x 21 1/2" x 2" Quantity:12-pack the more efficient a filterAny Kind of Filter's Extended Surface Pleated Filters outperform ordinary furnace filters with medium efficiency and are designed for lower pressure drop, and long service life which reduces HVAC equipment maintenance and energy costs. A higher MERV rating means that the air filter that you are about to purchase possesses a higher amount impurity filtration ability than your ordinary filter.