These universal pipette tips are made from virgin polypropylene material and are precision molded for an airtight fit to variety of pipettors to ensure laboratory standardization. A reference mark at 10 µL lets you check pipettor calibration and visually estimate sample size. Tips are packaged in racks for easy access. Tips are tested by an independent laboratory and certified to be RNAse- and DNAse- free, a trace metal certificate is available upon request.