Laboratory rubber stopper
（重定向自Rubber bung）
![(From left to right) Rubber bungs are aligned from size no. 1, 2, 3, 4, 6, 7, 8, 9, 10, 12, 13, 14, 15, to 16, respectively. (Comparing to the ruler)](/Images/godic/202502/08/Rubber_stopper_size3623.jpg")
A laboratory rubber stopper or a rubber bung is mainly used in chemical laboratory in combination with flasks and test tube and also for fermentation in winery. Generally, in laboratory, the sizes of rubber stopper can be varied up to approximately 16 sizes and each of it is specific to certain type of container. As the rubber stopper is used in many experiment, some specific experiment requires a specific material. For example, the M35 Green Neoprene is for chemical Resistance. For food fermentation, M18 white natural gum should be used. For high temperature application, red or white silicone rubber stopper should be used.