Potassium Iodide - 100% Pure USP Crystals - 31% K / 69% I, 100 grams (3.52 oz). 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. Excellent as a Lab Reagent or for any analytical purposes. Intended for lab or scientific use only. NOT for food, supplement, or drug use. There are no instructions with this material as Potassium Iodide has many different uses across multiple industries.