The sanding spong easily fits into the palm of your hand and is ideal for sanding a variety of surfaces. Due to it's shape, consturction and controlled flexibility the standard four side sanding sponge block can operate in the most awkard places. High-quality brown corundum is an extremely tough, wedge shape grain, for high speed penetration of tough materials without excessive shedding or fracturing of the grain. Great for Wood, Metal, Drywall, and Paint Hi-Performance, particularly suited well for grinding high tensile strength materials as hard woods and alloy steels.