These carboy caps will fit 3, 5, 6, 6.5, and 7 gallon carboys! The rubber is easy to clean and sanitize and the fact that the cap goes over the top of the carboy helps keep liquids from dripping in when it is removed! Handy dandy!
This cap will also fit into the neck of a Sanke Keg when the cap is inverted. See our Homebrew Hacks blog post for more info!