U.S. Silica Silurian 20-Grade Angular Filter Sand for Above-Ground & Inground Swimming Pools, 50 lb Bag – Washed & Screened for Cleaner Water, Enhances Filtration, Flow & ClarityBrand: U. S. Silica Color: White Features: High Powered Filtration: Angular shaped silica sand formulation delivers effective filtration by trapping dirt, leaves, and microscopic debris in both above ground and inground pool filters to help maintain clearer, cleaner water. Optimal Performance: Specially graded, angular grains are engineered at an optimal 20 level (0. 40mm to 0. 55mm) for strong entrapment, better flow rates, and crystal clear waters.