Sterile tips are packaged in racks of 96 with 10 racks in each case. Manufactured in a precision molding facility from 100% virgin polypropylene, United micropipette tips are DNase, RNase, and Pyrogen free. The highly smooth surface is hydrophobic to provide low liquid retention, increased accuracy and repeatability. Inner radial rings enable an airtight grip on the tip cone. Autoclavable at 121°C and 15 psi for 30 minutes.