Kimax® square flasks save valuable shelf space, with each flask taking up 25-30% less space than a round flask. Flasks are calibrated both "to contain" and "to deliver" (top line). Graduation rings and marking spot are blasted onto glass, and ST ground glass stopper is supplied. Designed from ASTM Specification E288, Class A unserialized requirements. Replacement ground glass stopper is Cat.No. 6-41900R.