Saf-T-Seal screw cap microcentrifuge tube caps fit Saf-T-Seal 0.5, 1.5, or 2.0 ml screw cap tubes and are suitable for use in vapor-phase liquid nitrogen storage, -80°C freezers, boiling, and autoclaving. An interior U channel in the cap keeps the ethylene propylene rubber (EPR) "O"-ring in place as the cap is tightened. Certified free of detectable RNase, DNase, and DNA. Tested pyrogen free. Autoclavable.