If you already have 2 argon regulators... just buy a bottle T. Been doing it for years. Saves having to buy a second bottle. I also suggest buying the largest bottle possible. Saves a ton of hassle.
There is a check valve option... When I bought there wasn't, Its not a necessity. I typically just run one regulator until I know I'll be doing lots of backpurge welding.
https://www.arc-zone.com/connectors-...h=13_673_2034&
If you dont have a second argon regulator, Hop on amazon and search "Dual Output Argon Regulator Flowmeter"
Any other questions, feel free to ask