These plastic clamps are used with the blue sealing gasket to help seal the lid of the f8 and f15 fermenters to the tank. Using the blue sealing gasket and the clamps forces the CO2 out the airlock in the lid. All of these items are sold separately. Some brewers say you need six clamps and some say none are needed, some say they use a brick on the lid with the blue gasket. We have in the past recommend no gasket before we developed the new blue gasket. The red gasket was difficult to use and the yeast works better without the pressure of a seal. This is one of the great things about brewing and wine making. You decided what works best for you. It is all in the taste. That is all that counts.