Solid version of FE494. A new stopper that fits a 2.8,3,5,6, or 6.5 gallon glass carboy. (DOES NOT FIT BETTER BOTTLE OR PLASTIC CARBOYS) Also fits a 500ml Erlenmyer flask. Made with a longer taper from a different material, this stopper does not pop out when wet. Much more reliable, it quickly became our stopper of choice for all applications involving these size carboys.