Calcium Hypochlorite is often used for water treatment (the chlorine kills bacteria) and as a bleaching agent. It's a fine granular product that is usually shipped in tank cars, but can also be shipped in covered hoppers if they are well sealed. It's safer to ship in its hydrated form (typically 5.5% to 10% water). Like many bleaching agents, its effectiveness is often measured in terms of 'available chlorine' -- the quantity of chlorine released when treated with acid. This product has 60% to 75% available chlorine.