Hogs Hair is a unique type of filtration media consisting of natural organic fibers. Only available in rolls. Replaces almost any size 1/2", 1" or 2" framed panel filter. Hogs Hair filters are passive electrostatic type products. Air running over the fibers creates an electrostatic charge to catch and hold airborne contaminants. Dirt loads throughout the filter's depth holding a lot more dust than other filters before requiring changing or cleaning.