Corning® 250mL polypropylene (PP) centrifuge tubes are ideal for applications requiring large volume centrifugation. Please check our Technical Information Listing for information on the physical and chemical properties of Corning plastic centrifuge tubes as well as important suggestions for safe use. -Each case of tubes contains a recyclable foam rack to facilitate handling. -Support cushions (Catalog No. 430236 for 250) must be used with this product unless the centrifuge rotor has appropriate V-bottom cushions. -Polyethylene plug seal caps. -Maximum RCF of 6,000x. -Tubes are sterile and certified nonpyrogenic.