No longer do you need to use harsh and messy chemical to remove rust. These Sandflex blocks will make short work of rust removal with just a little elbow grease. These Sandflex blocks work just like erasers. Just rub the Sandflex block on any rusty surface and rust will disappear. These Sandflex blocks are made from carbide grit imbedded within a rubber-like substrate. Since abrasive material is distributed throughout the entire block, as the block wears, new and sharp abrasive material is exposed. Sandflex block can be used wet or dry. Each block measures 3" x 2" x .75" in size. Set comes with one each of the fine, medium and coarse Sandflex blocks.