The regulator will depend on your tanks
Tank Compatibility: E-tanks generally use a CGA-870 yoke connection, allowing for easy, tool-free connection. M-size tanks often use a CGA-540 threaded connection, although smaller "M" series (like M6, M9) may use CGA-870
You can find them online at sites like Amazon or ebay. You will want a flow rate that runs up to 25LPM