Globe's line of disposable screwcap microcentrifuge tubes are available sterile or non-sterile. The sterile tubes include a cap with nitrile o-ring. The non-sterile tubes and caps are sold separately so that you have a choice of cap styles (with o-ring or without).
Note: All instruments and names of manufacturers mentioned herein are the trademarks of their respective companies and are used for reference purposes only. Globe Scientific Inc. expressly disclaims any affiliation to them.