Duckback is dedicated to making extremely high quality coatings that protect wood from harsh ultraviolet rays and shed rainfall like water off a duck"s back. 8.44 oz. Anti-Skid Additive. 100-percent ground walnut shells creates a slip resistant surface. Designed for both interior or exterior use. 40/60 grit is perfect for sidewalks, driveways, pool sides, decks, docks, ramps, stairs etc. Mix one package of anti-skid to one gallon of paint or other coating. If applying more than one coat of paint/coating add anti-skid additive only to final coat.