IDS Home Aquarium CO2 Needle Valve Guage Diffuser Pressure System DIY Planted Tank 2 Types Size(L*W*H): 1.6inch x 0.6inch x 1.18inch / 4cm x 1.5cm x 3cm (approx) Can fit 4mm(inner diameter) and 6mm(outside diameter) hose Ergonomically design, easy to install without using any tool Precise structure, durable stainless steel inner part with aluminum alloy to release CO2 by fine tuning