The Karcher AD 4 Premium is an ash and dry vacuum with a 17L tank. This means you don't have to buy a dust bag. The flat filter prevents dust particles from getting stuck in the vacuum. The exhaust filter also stops other dust particles, so the air blown out by the ash vacuum is free of dust particles. Is the filter clogged? With the push of a button, the product cleans the clogged filter to improve the suction power. The AD 4 Premium has a telescopic tube, so you always have a comfortable working height. It also has a parking mode. This means you can stably place the vacuum when you're not using it.