Portable Size: This scubas diving tanks refill adapter set has a portable size and is easy to store, you can put it into your tool bags to carry. Easy to Install: The install and removal process of this product is very convenient. No other tools are required. The design of this product allows you to fill your tanks quickly, which is convenient for outdoor use. Compatibility: 8mm fill valves size can be compatible with most standard scubas valves, and has a wide application. Preferred Material: The adapter is made of aluminium alloy material and the hose outside with steel wire, giving you a using experience. Pressure Meter&Hoses: The pressure gauge and hose are designed to give you a experience, you can notice changes in pressure at any time. Thread: 8mm Working pressure: 30MPA Hose length: about 500mm Colour: black Material: Metal Package Contents: 4 x Scubas Adapter with Hose Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.