I bought mine from JC Whitney...couldn't find it anywhere else. The kit consists of a thick hard felt polishing pad that attaches to a drill and a container of abrasive compound (I think it's cerium oxide) that you mix with water before use.
Though I did get a polish on my windshields, I ran into two problems I'd like to pass on. One was a large outside abrasive particle once got caught onto the abrasive pad and put nice swirly scratches on the windshield. You must thoroughly clean the windshield and molding crevices of any debris with a brush and garden hose.
The other problem was the instability of the pad when it was rotating. The drill kept rotating in my hand. Ideally, this kit shold be used with a 90° angled drill....better yet with two handles.
95 E320 Cabriolet, 131K