No guarantee: According to the instructions on the Kärcher homepage, the one for 191.-- has two pairs of rollers but the old cover, the one for 194.-- has one pair of rollers but the new suction head cover.

Good question. I got rid of the device after a short time. The roller stopped turning. Maybe the cover you are referring to is crucial. It was out of the question to claim warranty services due to the complicated shipping conditions. I would not recommend the device.