(1) CNG TYPE-1 cylinder seamless steel cylinder(2) CNG TYPE-2 cylinder welded cylinder, composite cylinder Material: 34CrMo4 /30CrMo, Outside Diameter: 279mm / 325mm / 356mm / 406mm Service Pressure: 20MPA Water Capacity: 40L 45L 50L 60L 65L 70L 80L 90L 100L 110L 120L 130L etc.