Hi dear!We are professional gas cylinder & accessories factory.1.We produce different standard cylinder for different countries.DOT standard for NA countries ,EN-ISO standardard for EU countries,and ISO9809 standard for other countries.And we produce many different sizes of gas cylinder ,from 2L-80L.2.We produce many different products such as oxygen regulator,oxygen concentrator, gas generator,gas cylinder valve,gas cylinder cap.3.We have 4 shops on alibaba ,and we are top1 gas cylinder supplier on alibaba.