Our PCP air tank comes with a professional air filling system with regulator pressure gauge to check the working pressure. Hose connections (included) has a 1/8 female quick coupling. It can be connected directly to the air compressor for filling (thread size: M18 x 1.5). Good quality carbon fibre tank used to charge gas, PCP paintball, air rifles, charge scuba, underwater breathing, clean energy, emergency escape, snorkelling diving, chemical industry, shipping, medical supply and fire fighting, etc. Large capacity: 3 L large capacity. no more more of the manggas when you are outdoors. Its workmanship is excellent that fully wrapped carbon fibre and fibreglass winding, making it lighter while with higher strength. Compared to conventional gas bottles, it has the advantages of light weight, long service life, 4500PSI high performance and good looking appearance. It can reach 50 Mpa according to our product tests and working pressure is 300 bar. High quality: We have used 6061 aluminium alloy as a material for the inner layer and the outer layer is wrapped in high-quality fibreglass and high-performance carbon fibre. Wear-resistant, shockproof. It ensures that the retaining gas is clean and pure. Professional manufacturer: Our company is one of the most professional manufacturers and suppliers of air compressors in China and we offer a comprehensive after-sales guarantee and technical support (24 hours online service)