Pyrex® Volumetric Flask, Class A, works certified, USP/ISO/DIN tolerances, 250 mL

Complies with ISO 1042 and DIN 12664, Manufactured from borosilicate glass 3.3, Calibrated to the tolerances required by the United States Pharmacopoeia (USP) which are tighter than those of ISO/DIN standards, Each flask engraved with individual serial number and supplied with certificate of calibration traceable to National standards, White enamel inscriptions, With Polyethylene stopper, 20mL and 5000mL sizes are supplementary to DIN range.