Heads up: part number 90520643 is not a DeWalt item — it is an original Black & Decker friction pad for power rasps/sanders. Below is a concise sales-style description you can use if you need the part to repair your tool.

Genuine Black & Decker friction pad (part 90520643) — replacement rubber pad for the underside of the arm on compatible power rasps/sanders. The pad is adhesive-backed for straightforward installation and is shaped to seat into the standard arm mounting on these machines. Nominal pad width: 13 mm. Designed to restore proper contact and reduce slippage where the sanding arm bears on the work or belt, so the tool runs true and sanding performance is recovered. Fits Black & Decker models KA900E, KA902E and XTA900EK.