These food grade silicone stoppers feature several vent holes lightly sealed with a silicone top flap. Gases can escape, but cannot get in. Just put the stopper on your carboy, and forget it. No worries about evaporation or water getting into your fermenter. This #7 size is pictured at left above, and fits virtually all glass carboys. Made in USA.<P>
Click here for a pdf of cleaning and dissasembly instructions.