KIMAX® Volumetric Flasks with PTFE Stoppers have a graduation ring blasted on the neck. They are supplied with a PTFE stopper with a color-coded handle. These volumetric flasks are calibrated to contain. With a marking spot on 10 mL and larger sizes. The 1 mL and 2 mL sizes are test tube shaped. All other sizes are of a conventional flask shape. .The 5 mL and larger sizes are designed from ASTM Specification E288, Class A unserialized requirements.