VentSep, a special 1-liter or 2-liter separatory funnel with a built-in relief valve, can be used on Glas-Col's Bench-top Shaker or either of the Glas-Col 3D shakers. That means you can shake up to eight 2-liter funnels or ten 1-liter funnels at once without worrying about pressure buildup. What's more, VentSep features a screw cap instead of a penny-head stopper. As a result, VentSep is safer to use in the laboratory because the screw cap doesn't need restraining and won't come off at inappropriate times, though it will come off easily when you want it to. VentSep will vent gas pressure over 1 psi automatically. This means you reduce the possibility of unsuspected pressure buildups that could cause exploding glass and personnel injury. As a result, vigorous hand or machine shaking can be done with confidence.