Product Name: Air Flow Control Valve; Material: Stainless Steel; Outlet Diameter: 4 mm/0.16 inch Fits Air Tube Diameter: 4*6 mm/0.16"×0.24"; Overall Air Valve Size (Each One): 30 × 21 × 8 mm/1.2" × 0.84" × 0.32" (L × W × H) Control the flow of vital oxygen from a pond aerator or aquarium air pump using this handy valve. Used in aquarium and aquaculture applications. The air valve can be connected to aquarium tubing.