Filter cartridge.

Filter insert, in particular block-shaped construction, consisting of a plurality of arranged in a zigzag-shaped folding of fold walls for a in the direction from one edge region of the zigzag folding towards the opposite edge region of the fold by the use of light passing medium to be filtered, consisting of a filter medium projecting with from each fold wall in the direction of an adjacent pleat wall projections formed by embossing, wherein the projections of adjacent facing fold walls to the distance maintaining adjacent to each other and the filter medium can be hardened at least in the region of the projections by thermal effect. The filter medium (11) from a thermoplastic material existing fibers by welding under heat in the region of the projections (30, 36, 37) and / or fold edges (23 to 29, 40, 55 to 57) the medium (11) in themselves compress or stiffen or connect with appropriate material.