All kind of CNG cylinder adopts production process of billet piercing and drawing, and add inside grit blast treatment process. We are one of the biggest supplier for industry gas cylinder especially for CNG Cylinder.CNG cylinder detail specification--Standard: ISO11439--Water capacity: from 20L to 180L--Diameter (mm): 232, 267, 279, 325, 356, 406--Material: 30CrMo/34CrMo4--W.P.: 200 bar