Buon Vino Stopper with Airlock Hole
$1.25
Small Stoppers fit ALL 3, 5, 6 and 6.5 gallon glass carboys - universal fit.
Medium Stoppers fit something we can't figure out.
Intermediate Stoppers fit Mainbrew's 3, 5 and 6 gallon PET carboys.
Large Stoppers fit some oak barrels.