Generally, centrifuge tubes or centrifuge tips are tapered tubes of several sizes developed from glass or plastic. At times they may vary in capacity from tens of millilitres, to much smaller capacities utilized in Micro Centrifuges which is used across-the-board in molecular biology laboratories. The most usually encountered tubes have size and shape of a normal test tube (~ 10 cm long). Micro Centrifuge particularly accommodate Micro Centrifuge tubes with capacities from 250 μl to 2.0 ml. These are exclusively made of plastic. Plastic centrifuge tubes, typically Micro Centrifuge tubes are less expensive. Water is preferred when Micro Centrifuge tubes are being used.