These locking-lid microcentrifuge tubes feature a pierceable cap that snaps closed and locks into place in a convenient one-handed operation. Tubes are ideal for use in sample-handling applications, including centrifugation, boiling and freezing of specimens, incubation and storage. They are made of polypropylene and have graduation marks to facilitate volume estimation. Available in three sizes and a range of colors. Each size is also available in an individually-wrapped sterilized version, natural color.