Cylinder is made from 304 stainless steel. Needle valves are 316 stainless steel, Kel-F® and PTFE and have 1/4" female NPT threads. A Mininert® valve is in-line between the sample cylinder and one valve, to allow syringe needle sampling directly into the cylinder for sample withdrawal or standard preparation. 100psi maximum pressure because of the Mininert valve.