Made of high quality 100% pure virgin medical grade polypropylene so you won’t find recycled plastics in our tips. Every lot is lab tested and certified free of detectable Nuclease (Rnase/Dnase), Endotoxin (pyrogen) contamination, and certified to U.S.P. results. Resins are pre-tested for metal contamination. Tips are racked and packed in a teal rack. These racks are made of polypropylene and are autoclavable repeatedly. They have sturdy latch hinges that won’t come apart like lesser quality tip racks and a special snap lock designed so that it will not catch on your gloves.