Merv 8 Pleated Air Filter - 27" x 31" x 1" Quantity:12-pack if not you can measure

if not you can measure it or check the HVAC unit and the owner‰۪s manual

Unlike some permanent custom air filters

One way to overcome this problem is to increase the surface area of the filter media

In general

Merv 8 Pleated Air Filter - 27" x 31" x 1" Quantity:12-pack if not you can measureAny 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.