I had a sample with me, but you won't get far with that. So be sure to order one at the same time to save on postage. There are half-litre bottles, RM500 (6.295-772.0) for the inside of the window and RM503 (6.295-840.0) for the outside. I also ordered the corresponding pads at the same time: Inside 2.633-130.0 and outside 2.633-131.0. The narrow suction nozzle (2.633-512.0) can also be very useful. Have fun cleaning - not in the sun and the windscreen should be well moistened, otherwise it will smear. With a little practice, it will be fine.

Unfortunately, the WV6 Plus was unusable for us. You can't vacuum horizontally with it, as was the case with earlier models. It is therefore not suitable for showers and windows with rather thick frames. We then gave it away.
I then bought the professional Kärcher WVP 10 model (with or without US) and am very happy with it. You can vacuum in all directions with it. It can even suck up spilt liquids from the floor. It also has a rechargeable battery with charging station. This allows the battery to be changed when it reaches the end of its service life or, with 2 batteries, the WVP 10 can be used continuously.