Grinding sponge, aluminum oxide-sprinkled on 4 sides, corundum, one narrow side and one wide surface in single grain.Double sponge grain, carrier made of very flexible polyurethane foam, synthetic resin, dry and wet can be used. The friction can be rinsed.To remove rust, paint. For cleaning and sanding synthetic resin paint, acrylic paint for painting. Good for sanding window and door frames before painting.