The Compact HEPA filters are mainly used for the clean rooms to control the particulates that are larger than 0.3μm.The common depth is 70mm/90mm and adopts mechanical compression seal .But the seal effect isn’t as well as gel seal,so there’s a tendency to be replaced by gel sealed compact HEPA filter.There are two kinds of sealing:CR hand-made sealing and PU automatic foaming.Considering the factor of performance and efficiency etc ,most of LENGE products produced by PU automatic foaming which will be much better.