Merv 11 Pleated Air Filter - 20 1/4" x 23" x 1" Quantity:12-pack some just refer to them

some just refer to them as electrostatic filters

Can be ordered in packages of 2 each only

these can be purchased in any conceivable size

You may know them as washable air or even permanent air filters

with each stage capturing progressively smaller particles inside the filter

Merv 11 Pleated Air Filter - 20 1/4" x 23" x 1" Quantity:12-pack some just refer to themAny 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.