Eppendorf 022363557 Polypropylene Flex-Tubes Microcentrifuge Tube, 1.5mL Capacity, Green (Case of 500) Flex-Tube lid is easy to open and close for ergonomic operation Polypropylene provides high resistance to chemicals, mechanical stress and temperature extremes Manufactured without the use of slip agents, plasticizers and biocidessubstances that have been shown to leach from plastic consumables into the sample and negatively affect bio-assay results Precise lid sealing for minimal evaporation rates during long-term storage Frosted lid and surface on the side for easy labeling