Made of high quality plastic PMMA material in clear color, designed with 12 sockets, two layers, each socket is 16mm/0.63" diameter. | Ideal for laboratory, can provide clear view of the tube contents and convenient insertion and removal of tubes. | For 10ml Test Tube. | Test tube set for laboratory and party, holding the tube firmly, avoiding the test tube damage effectively | Works great to hold lip balm tubes to be filled and to cool so they don't tip over and spill.