The individual pockets are welded conically and are connected so that they are leak-tight using the single frame structure. Frames made of galvanised steel or plastic are used as standard. The frame depth is 25 mm (optional: 20 mm). We can also provide an optional PP flat seal. If the filter media are multi-layer polypropylene melt-blown synthetic filter media or glass fibre filter media, the individual seams are sealed using hot-melt adhesive to prevent dust penetration.