Conical centrifuge tubes are made of premium polypropylene for clarity and centrifugal strength. Tubes and caps may be frozen at temperatures as low as -86˚C. The maximum centrifugal force is 12,000xg for the 15ml tubes and 15,000xg for the 50 ml tubes*. Caps have a flat top surface for easy marking and labeling. Eco-Plastic racks are a recyclable alternative to standard foam racks when it's time for disposal, or can be broken down into a compact, flat package that is easy to store between uses. • Sterile, RNase, DNase, pyrogen and cytotoxin free• Compatible with standard rotors• Frosted marking surface