Patented Harveys Mini Curve Block Salt top quality. Harvey Block Salt is formed by high-pressure pressing fine salt under carefully controlled conditions to ensure consistency, purity and quality. The Curved Blocks are hard compressed, non-dusty and have good curved shapes and dissolve slowly to form a quality brine solution. Compliant with British Standard BS EN973, Harvey Block Salt is Grade A/food quality salt, pure with no additives, including no anti-caking agents or nasties that could damage your softener. Harvey Arc Block Salt is compatible with the Harvey Arc, Minimax Innova, and TwinTec Cobalt water softeners.