Each separatory funnel holder will hold one funnel, and you can use up to four holders which mount to the platform without fasteners. While the rear support of the funnel holder remains stationary, the front part holding the funnel can be released and rotated 360°. This permits the funnel to be filled, inverted for shaking, and then reinverted for addition and/or extraction, all while the flask remains in the holder. This also helps to eliminate breakage of glassware caused by handling. When using standard funnels with glass, plastic, or PTFE stoppers, our stopper retainers are required.