Potassium Iodide, USP Grade 100 grams. Fine Crystals Powder, USP Go to amazon.com Related posts Check expert advices for iodine crystals? DescriptionYou are buying high quality potassium iodide USP/ACS grade crystals 99.9%-101.5%. This is the highest purity and quality in the USA. Made and packaged in USA. Same day ship! CAS# 7681-11-0, F.W. 166.00