The application of synthetic fabrics instead of cellulose based filter papers in panel filters has many advantages. Synthetic fibres have very good filtration properties. Contaminants absorptivity is much higher, maintaining comparable filtering efficiency, which allows making the filters with fibres instead of traditional filter paper in larger sizes. However the application of these fibres is limited due to its low rigidity. The solution is injection moulding of the fibre filter into a rigid frame. Sometimes pleating the fibres with special plastic nets is applied for increasing the rigidity of the filter medium and protection from damage during exploitation.