Silicone,Tube Diameter: 4mm internal diameter and 6mm external diameter Aquariums, fish ponds, fish ponds, the oxygen pump dedicated connection pipe, is essential supplies oxygen pumps and other equipment output This air line is with a standard size (4mm internal diameter) that fits most standard aquarium air pumps and air stones. It can be used for Hydroponics, Aquarium, Pond . Very light and soft, Professional oxygen pump hose for fish Length: 1M/5M/10M(optional),Color: White