RIA vials are generally used in radioimmunoassay - a scientific method used to test antigens without the need to use a bioassay. The polypropylene vials are translucent and can withstand 3000 RCF during centrifugation. Can be used with common acids, alkalies, and solvents at room temperature. Autoclavable. The polystyrene vials are transparent and can withstand 1400 RCF during centrifugation. Can be used with mild bases and weak acids, but not organic solvents. Non-autoclavable. Caps are sold separately and are compatible with both versions of vials.