Advantages of the TPP racks for centrifuge tubes 15 ml / 50 ml: alpha-numerical inscription to identify your samples a convenient form heat resistant autoclavable material - racks need to be disassembled when heat treated collapsible for storage: TPP racks with the “click” system are quickly assembled and disassembled. They show no inhibitory burrs on the insertion holes Additional advantages for the TPP rack for tissue culture flat tubes 10: transparent top protection rim that prevents horizontally stored tissue culture flat tubes 10 from shifting