Antique Pharmaceutical Erlenmeyer flask with a Fermentation Extension Part-Plug . The reaction vessel is plugged with  the Extension Part-Plug : a little water is poured in there - this helps the formed in the flask gases to leave, but not the outside air to enter. It is usually used to study fermentation processes or similar bacteriological phenomena. They are cleaned and in an excellent condition. It is 40 cm- high, the widest part has diameter 9 cm.