Globe Scientifics dual position cap is produced from low density polyethylene (LDPE) and is ribbed for easy handling. The cap is specially designed to provide aerobic or anaerobic storage of culture samples. When snapped into the tube, the cap provides a leak-resistant seal. Also see our complete line of culture tubes under the Test Tubes & Vials category. Note: Leave the cap in the loose position for aerobic work and in the sealed position for anaerobic cultures.