Meanwhile, we have switched to a Kärcher NT 25/1 AP and have equal moreover taken a pack with non-woven filter bags. This officially not fit for NT25, but in Kärcher shop compatibility we were assured and the parts actually work properly. Whether dust from drywall, sawdust or small wood chips, stones, etc .. the bag holds and the suction power is significantly better than the previously used bags in Nilfisk ...