Type 1 CNG Cylinders are of an all steel design. The Type 1 design is considered the most durable On-Board Cylinder design and the most economical. The cylinders are designed and manufactured to the ANSI NGV 2 — 2007 & FMVSS — 304, ECE R110-1, ISO 11439-1, NZ5454-1, IS15490,ISO11119-1,