These flasks allow growth and turbidity reading at selected intervals without sampling. Simply tilt flask to allow filling of the sidearm and insert sidearm into colorimeter or spectrophotometer. The side tube is scratch and striation free. Designed to operate on a platform shaker, the flask holds approximately 350 mL to the base of the sidearm. Material cannot enter the sidearm when on the shaker. The break- resistant lip accommodates a cotton plug or stopper. These flasks are manufactured from Wheaton 33 low extractable borosilicate glass that conforms to USP Type I and ASTM E-438 Type I, Class A requirements.