New, original wooden box, laboratory surplus. Platinum-Iridium ring by Fisher Scientific for surface tensiometers, ring model 14-812-5, 20/21. Approx. dimensions: Ring diameter 20mm, total height 59mm, ring weight 0.034 oz. For use with a surface tensiometer to determine the apparent surface tension and interfacial tension of liquids. The ring method is fast, accurate and applies to many educational, biological, medical and industrial determinations in connection with water, petroleum products, detergents, pharmaceutical materials and other substances.