SureSoft's Cubes Plus with Resin Clean Salt is produced by standard solar evaporation technology from the Great Salt Lake in Utah. The salt is washed for removal of impurities, kiln dried, compacted, screened, and quality control tested. North American SureSoft Salt Solar Cube Plus is manufactured in compliance with standards from the American Water Works Association and is certified by the National Sanitation Foundation under standard NSF/ANSI 60. | Sure Soft Cubes Plus with Resin Clean | Size 50 lb