Extra Coarse solar salt is made with high purity salt crystals. Designed to dissolve easily and keep softeners running at peak performance. Made with high-purity salt crystals and no additives. Minimizes residue build-up and can extend the life and reduce the maintenance of your system. Can be applied to commercial water boilers or used as a residential water softener. | Salt Depot Super Soft 100% Natural Extra Coarse Softener Salt | Size 40 lb