Pocket air filters are often installed in HVAC systems in auto shops, data centers, food and beverage plants, industrial sites, and schools to trap contaminants in the air stream and boost indoor air quality. They also keep the contaminants from building up in the equipment and damaging it. These filters are best suited for applications where air is constantly flowing through the filter since they may deposit some captured material back into the air stream when they deflate. Also called bag filters, pocket filters have a bag-like filter element that is stitched into pockets. They trap more particles than non-pleated panel filters and need to be changed less often. These filters have a MERV (minimum efficiency reporting value) rating of 8 to 14. A filter\'s MERV rating measures how efficiently a filter traps contaminants in the air stream based on the size of the particles it can effectively capture. The higher a filter\'s MERV rating is, the more effectively it traps small particles.