Our screw top transport tubes are ideal for sample collection, sample storage and transport. The strong construction and leak-proof threaded caps make them safe and convenient. Each tube has molded graduation marks and a frosted area for writing sample identifica- tion information. The tubes are made from virgin FDA grade polypropylene and the caps are made from virgin FDA polyethylene. The vials are not autoclavable. All tubes have an interior conical bottom and an exterior skirt which allows the tubes to stand without a rack. The tubes come with the caps in a separate bag.