Specifically formulated for rock climbing A safe drying agent is added to the highest-quality magnesium carbonate for maximum sweat absorption Packaged in re-sealable, zippered bags. 100% Magnesium Carbonate Available sizes: 2.5 oz. (70 g), 4.5 oz. (127 g), 9 oz. (255 g) and 15 oz. (425 g) The #1 selling brand of climbing chalk in America!