Filtering flasks (also known as a vacuum flask) has heavier walls than a standard Erlenmeyer flask to withstand the effects of vacuum filtration. A side arm with hose allows flexible tubing for connection to vacuum pump, aspirator, or house vacuum. While filtration, the filtrate enters and is held in the flask while the sample or residue remains on the filter paper in the funnel. Filter flask can also be used as a vacuum trap in a vacuum line. Select from borosilicate glass, safety-coated glass.