[Healthy and non-toxic]: Made of PVC material, long-term use, healthy and non-toxic. [Transparent and flexible]: Transparent material can prevent the accumulation of deposits; the flexible tube is suitable for various scenes. [Widely Used]: Great accessories for your aquarium tube, air pump, check valve, bubble stone connection. [Dimensions]: Inner diameter 4 mm, Outer diameter 6 mm, Length 20 meters. [Material]: PVC; [Color]; Transparent