The curved salt is made specifically for the HarveyArc. It fits around the curve of the water softener to fit the space efficiently. The curved salt is lighter (2.15 kg per block) and smaller, so easier to handle. The blocks can be stacked for a higher salt capacity – meaning you have to refill less often. Made from quality, food grade salt, doesn’t contain any anti-caking agents or nasties so it will keep your Harvey running beautifully.