Sciencent Lab provides twin purpose rack for both 0.5 ml. & 1.5 ml. micro centrifuge tubes. Each side has 108 holes for both 0.5 & 1.5 ml. MCT's respectively. MCT Twin Rack has transparent top which provides an excellent view as well as a protection cover for the tubes stored. Each face of the base has a unique alpha-numeric index so that we can easily identify the tube.