Kimble 20039P KIMAX Class B Glass Graduated Mixing Cylinder with PE Stopper has a "to contain" scale of durable white ceramic enamel. “TC” appears on each cylinder and indicates the cylinder is calibrated to contain. The enlarged top of the stopper protects the neck if the cylinder is knocked over. Stopper made from linear, high density polyethylene. Replacement stopper is 28160R. Designed from ASTM Specification E1272, Style II, Class B requirements. Manufactured from 33 expansion, low extractable borosilicate glass conforming to USP Type I and ASTM E438, Type I.