This stopper will fit a 2.8,3,5,6, or 6.5 gallon glass carboy (please note: Will Not Fit a Better Bottle Or Plastic Carboys). Will also fit our 500ml Erlenmyer flask. Made with a longer taper from a different material, this stopper does not pop out when wet. Extremely reliable, it is our stopper of choice for all applications involving these size carboys.
Also will fit a 12 or 22 oz beer bottle when used upside down.