2000 ml borosilicate glass flasks work great for average sized yeast starters. Use either the 46-50mm foam stopper or a #9.5 rubber stopper with an air lock. To further enhance overall yeast cell count and vitality, use a stir plate in conjunction with the flask to continually introduce oxygen through a breathable foam stopper and into the flask.
NOT FOR USE WITH ELECTRIC STOVES OR HEATING PLATES! Can be used on gas stove or in a double-boiler. If you only have access to an electric stove we highly recommend making your starter in another vessel and transferring to your sanitized flask.
To prevent breakage, do not immediately submerge flask into ice bath following boiling. Please allow flask to drop in temperature for several minutes before cooling in ice bath.