This rack holds 50 ml conical tubes, 15 ml conical tubes and a variety of 1.6 or 2 ml and 0.6 ml tubes. This is no ordinary 4-way flipper; a patented modification enables racks to interlock by pressing the 1.6 ml and 0.6 ml sides together. Flip the 15 or 50 ml tube side over, attach the 0,6 ml tube wells to the 1.6 ml tube wells and you now present twelve 15 ml wells and four 50 ml wells on the same side. All of the 4-way flipper racks are constructed of polypropylene.