The HT (high temperature ) type filter is manufactured by using thing glass fibers enclosed in a galvanized metal frame. It can withstand temperatures up to 300?C and its efficiency, depending to the type, can be between 55% to 95%. Due to its special characteristics the HT type filter is appropriate for the prefiltering of paint booths or other applications where high temperature conditions occur. They are distributed mainly in standard dimensions in order to be attached on the air ducts with the relative dimensions.