uxcell Aquarium Air Flow Control Valve Double Row 12 Branch Outlets 15 x 6 x 2.3 cm Material : Metal;Color : Silver Tone;Design : Dual Line 12 Way Outlet Overall Size : 15 x 6 x 2.3 cm / 5.9" x 2.4" x 0.9" (L*W*H);Fit Tube Dia.(Outlet) : 4mm / 0.16";Fit Tube Dia.(Inlet) : 18.5mm/0.73" Suitable for high power air pumps, with 12 individually controlled outlets. This 12 way aquarium air control valve allows you to distribute air to each tank as much as you wish. A great item for your aquanrium and fish tank.