EcoPlus 728460 Air Manifold T-Style Pump, 1/4" Inlet to 4 Valve 3/16" Outlet Allows the adjustment of air flow or more air stones or air diffusers The manifold has individual barbed valves The valves controls the outlet of air to your air stones or diffusers They also allows excess air pressure from the pump to escape to decrease pressure on the diaphragm of your pump