Pipetman pipette tips are made of 100% virgin polypropylene making them naturally hydrophobic so you dont have to worry about coatings or treatments leaching into your valuable samples. To help prevent contamination, the non-sterile, autoclavable 96 tips are loaded without manual intervention. The non-sterile Tipack racks are sealed with a security sticker, fully autoclavable, and they will resist being autoclaved several times. Sterilized Pipetman Tips are irradiated by gamma-rays for more efficient sterilization, and are delivered with a certificate of sterilization, specifying the date of irradiation. Sterilized Pipetman Tips are certified free of detectable Rnase, Dnase, DNA, RNA and protease.