The funnel holder will accommodate up to three funnels at once, depending on size, and can hold funnels as large as 500 ml. You can mount one or two of these holders on the shaker base. Just load the funnels with the stopcock down, adjust to the desired shaking position, and turn on the shaker. The funnel is secured by an easily adjusted yoke, and the stopper is held in place by a built-in elastic band. If youre mixing materials that create pressure while being shaken, the pressure can be relieved automatically with the Snorkel Stopper, which is substituted for the regular stopper, and is held in place with the elastic band. It automatically relieves pressure over one pound (psi).