Containers are made from PPCO (a copolymer of polypropylene and HDPE). PPCO offers a higher temperature range while maintaining good impact strength. All lids are made of LLDPE. Designed to simplify and standardize the handling and storage of specimens. The containers are inert and cannot be attacked by formaldehyde or weak acids or bases. Will resist freezing or boiling. They have long shelf lives and are easily disposable. Sturdy enough for reuse. Easy to store, requires little space.