Description General description Class A, Pyrex • Complies with ISO 1042 and DIN 12664 • Calibrated to the tolerance required by the United States Pharmacopoeia (USP) which is tighter than those of ISO/DIN standards • Each flask is laser etched with an individual serial number, batch code and date of manufacture • Conformity ′H′, certified • Manufactured from chemically resistant Pyrex glass • Inscriptions in white enamel • Polyethylene stopper Legal Information PYREX is a registered trademark of Corning, Inc.