DuoClickCulture Tubes feature a unique patent pending screw closure system DuoClick tubes completely eliminate the excess force splashing and general frustration of traditional snap-cap culture tubes The advanced cap design includes two distinct positions for aerobic and anaerobic culturing (see image no 2) Just rotate the cap to the first click to secure the cap in the aerobic position Or rotate it past the second click for a leakproof airtight seal for anaerobic culturing DuoClick tubes are available gamma sterilized with screw caps attached and in our exclusive ready-to-use rack packaging These plastic disposable STERILE culture tubes can arrive in two different material types Polypropylene and Polystyrene Polypropylene (PP) tubes can be centrifuged at up to 4000 x G Maximum of 1400 x G for polystyrene (PS) tubes New patent pending screw-cap Aerobic culturing at first click Anaerobic after second click Printed graduations Flat markable screw-cap