Conical/Erlenmeyer, Narrow Neck with Graduations. New, affordable, high quality range of Conical Flasks made from durable 3.3. Borosilicate glass. Superior chemical and heat resistance. Complies to ISO 1773 Standard. 100ml Inner Neck Diameter 30mm. 29mm (bottom) rubber stoppers will fit this product. See Product numbers 1158, 1162 and 1493.