High quality materials: Made of stainless steel, air does not leak and is durable. Size: The outlet diameter is about 4mm and the inlet diameter is about 4mm. about 4mm. about 8mm, which is suitable for most oxygen pumps. Simple operation: the splitter is connected to the tube of the air pump, manually controlling the flow of large oxygen or turning the pump on or off air valve. Perfect design: Control the flow of vital oxygen from your pond aerator or aquarium air pump with this handy air control valve. Range of use: can be used in aquariums, aquariums, aquaculture, etc.