Aquarium air pump accessories for standard air tubing Made of soft plastic, the air tubing is durable enough to withstand wear and tear. FITS ALL STANDARD INLETS: Standard size (4mm ID), fits most aquarium air pumps and standard air stones. Transparent, very light and soft , easy to hide and mix, perfect for any aquarium and disappears in water. Safe and non-toxic, will not harm your fish. Scope of delivery: 1 oxygen tube, white 20m long, inner diameter 4mm