Deep Pleat Heps Filters are the last line of defence against particles larger than 0.3 um in a clean room. To obtain a high dust volume, the filter media uses an ultra-thin glass fibre with each pleat spaced uniformly by hot-melt glue. The media room can be used in its entirety. Deep Pleat Heps Filters are safe to use. Metal screens with power coating are used on both sides of the air filter to prevent media damage.