These Sandflex blocks are a godsend when it comes to quickly cleaning up your tools. It works like an artgum eraser, but has tiny abrasive particles imbedded in it to make removing sap, crud and rust from your tools a snap without the danger of damaging the tools cutting edge. It is also very handy for removing water salts from the edge of a bonsai pot. A German made product that you'll wonder how you ever got along without. 3-1/4" x 2" x 3/4" .