HDX filters are constructed of a durable, moisture-resistant frame with wire supported media for strength and rigidity. The wire-backed Pleated media offers a large surface area which increases the filter's dust-holding capacity and improves its efficiency. The air filter media can be charged electrostatically which means it attracts, captures and traps particles that would otherwise bypass the filter. The air filter's media is rated between a MERV 8 and 13, which is 1-component of the FPR Rating. FPR or the Filter Performance Rating, is composed of 4-measurements for classifying air filters. Every rating includes 4-elements: MERV rating, E1 efficiency, pressure drop and dust holding capacity. MERV stands for the Minimum Efficiency Reporting Value and measures how well a filter traps particles. The higher the rating, the few particles getting through. E1 efficiency explains how well it traps the smallest particles. Pressure drop measures how much energy the HVAC unit will use to force air through the filter. Dust holding capacity describes how much dust a filter will hold in its lifespan. HDX filters are easy to replace making change-outs quick and keeping indoor air quality at its optimal level while protecting your HVAC unit and allowing it to perform efficiently.