Kimble kimax ray-sorb class a volumetric flasks with color-coded ptfe stopper these flasks are ray-sorb processed to protect your light-sensitive contents from short-length light waves. Calibrated to contain with a marking spot supplied with a ptfe standard taper stopper having a color-coded handle replacement stopper is 41901r designed from astm specification e288, class a unserialized requirements manufactured from 33 expansion, low extractable borosilicate glass conforming to usp type i and astm e438, type i, class a requirements and then ray-sorb processed. Warning: this product can expose you to chemicals including tetrafluoroethylene, which are known to the state of california to cause cancer. Prop 65 warning