Ai 24/40 standard taper joint, heavy wall oval-shaped, round bottom flask. Glass material: high borosilicate glass 3.3. Glassware does not have warranties. Glassware may have minute blemishes that will not affect the function. If you believe there are imperfections on your glassware, please contact us. We check all our inventory and make sure no defective glassware is sent to our customers. 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.