I was desperate to get a new filter for my WD4 vacuum so I ordered one from an independent vendor. First, they sent me the wrong one and secondly, they gave me some trouble getting a refund. I should've come here first. Karcher know their stuff best. The sent me exactly what I needed. I received it pretty quickly and they follow up to make sure that everything was fine. This is a top notch company. Keep up the great work!
These do cost a decent amount for a single filter, but they work well and for a long time. On one I used for a long time, the rubber gasket around the outside of the filter cracked. But that wasn't very surprising being that I used it heavily for two months.