MesoIridium is .998 pure iridium nanoparticles in colloid form, a TRUE iridium colloid, which means 100% iridium particles with no ionic content. Highest particle surface area. Highest bioavailability iridium colloid product, due to small particles. Small iridium nanoparticles, typically between 15-20 nm. It is an all natural mineral supplement. Made with the highest purity, sterile reagent grade deionized water. Does not require refrigeration after opening. Infinite shelf life. MesoIridium is non toxic (per Material Data Safety Sheets). Concentration is 10 ppm minimum. Please see our web site "purestcolloids" or our company information here on amazon for more technical information on colloidal iridium. MesoIridium is a trademark of Purest Colloids, Inc.