MicroStandards™ are available in diameters from 1 μm - 200 μm. Larger diameters are available on request. They are suspended in aqueous medium with trace amounts of an antimicrobial agent and proprietary surfactant for optimal colloidal stability. For ease of dispersion they are packaged in 20 ml dropper tip bottles at diameters and optimal concentrations for each diameter in the MicroStandards™ range. Each product is provided with a certificate of traceability stating the certified mean diameter and the expanded uncertainty. Product and lot specific physical data such as standard deviation, C.V., composition, density and refractive index are provided, but not certified.