These tips are guaranteed free from Human DNA, RNase, DNase, Pyrogens & PCR Inhibitors. They are made from medical grade virgin polypropylene material and are graduated for accurate measurements. The tips have a universal fit design that provides an airtight fit on most brands of pipettors. They are available in bags, racks, and reloading stacks. Three tip types are available: Standard, low retention, and low retention filter tips. The tips are manufactured in a cleanroom using fully automated equipment.