Pocket Filter Booths The air to be filtered is pulled through two filters, the pre-filter and the pocket filter, passes the fan, and is then pushed via a last filter, for a complete of 3 filters. The pre-filter, either in a body or a rolled media, catches the largest particles. The pocket filter has a higher surface area region due to the pocket design and collects the smaller sized micron particles passing via the pre-filter. The last filter collects any particles escaping through or around the...Read Full Post »