Diamond Crystal Bright & Soft Water Softener Pellets are NSF certified ;Since 1944 NSF certification is your assurance the product has been tested and complies with strict standards and procedures by one of the most respected independent certification organizations including regular on-site inspections of manufacturing facilities and regular re-testing of products to ensure they continue to meet the same high standards required to maintain certification ;They are a premium-purity water softener salt containing up to 99.8% pure salt ;Virtually 100% water soluble, these pellets are specially formulated to prevent mushing and bridging in the brine tankhelping to keep your water softener clean and trouble-free