I ordered this product after having watched videos and opinions. And indeed, this robot is perfect, impeccable work ouf the chore of windows behind me. Namely anyway, only dry, it will not happen much. So the manufacturer that also sells an ad hoc spray, should report that to moisten the pads is essential, I applied the advice of a buyer in his commentary, namely use household vinegar particularly if a greasy stains. And the result is stunning. Also, buy the top model (ie this one) is really not money lost. It really is quieter and more efficient A highly recommended. Super fast shipping by Chronopost