Twice I have had ice slide off the roof of my 2008 Cayenne and break-off the little black plastic cover at the center of the rear hatch wiper arm. Unfortunately Porsche only sells the plastic cover as part of the Tipswitch assembly that opens the hatch glass (part number 955 628 320 04) at a cost $ 95.94 plus tax. After paying this price twice I have recently discovered that an exact aftermarket replacement is available from several vendors on Amazon.ca for under $20 including shipping. Order a couple and save yourself a bundle of money!