Our premium purity water softener salt contains up to 99.6% pure salt. Formulated for use where iron content in water is high, it contains an FDA-approved additive that helps prevent rust stains on laundry, fixtures, sinks and tubs. Virtually 100% water soluble, it also minimizes mushing, bridging and rust buildup in your brine tank-helping to keep your water softening unit running smoothly. Size: 40 Lbs Compacted, pillow-shaped briquettes of sodium chloride. Contains Citric Acid, which helps to prevent rust discoloration on tubs, toilets, sink, dishes, cookware and laundry. Also contains Sodium Hexametaphosphate, which improves the product"s resistance to mushing and bridging. Intended for use in regenerating ion-exchange resin in both household and commercial water softeners, and can be utilized effectively in all types of water softening units. This product is designed for use where iron fouling is a problem. DO NOT USE WITH CHLORINE-TYPE CLEANSERS. May cause mild skin irritation. Packaged in polyethylene bags for added moisture protection.