Durable, machine-blown body. Heavy beaded tubing neck. Flasks feature a sharp graduation line and large white block letters. A ground glass stopper is included. Meets Class A specifications per ASTM E288. Batch certified. Our volumetric flasks feature QR code integration to facilitate quick and easy access to certificates of calibration, certificates of conformity, and user manuals where applicable. This is first of its kind innovative technology only available on United glassware. We recommend the NeoReader app for scanning QR codes. Simply point your smartphone to the QR code printed on the flask. Enter the serial number when prompted, and the app automatically takes you to the certificate screen.