KIMBLE 28016 KIMAX RAY-SORB Class A Volumetric Flasks with Color-Coded PTFE Stopper. These volumetric flasks are RAY-SORB® processed to protect light sensitive contents from shorter wavelength light. Flask is calibrated to contain and has a marking spot. Supplied with a PTFE Standard Taper stopper having a color-coded handle. Replacement stopper is 41901R. Designed from ASTM Specification E1404, Type II, Class 2 requirements.