TUBE, CENTRIFUGE W/RED SCREW CAP 12X75MM (250/BG,4BG/CS) Globe's popular 12 x 75mm test tubes are molded from premium grade polypropylene (PP) for impact strength and stability to common acids, alkalies, and solvents The screw caps come attached to the tubes and are designed to be leak-tight allowing the tubes to be used for storage or transport Max Spin Rate: 3,000 RPM