Okay one step closer to stable co2. I have an Ada on/off adapter, a needle valve, tubing and a tank full of co2 (20oz). The opening of the on off adapter was 1/8 inch od threading and the needle valve is 1/4 od threading. My question is does outer diameter threading apply to any other threading? Npt? I got a reducer to fit the Ada to the needle valve but I need a 1/4 inch female to female coupler and was wondering if I could find a threading similar to od or better yet an 1/8 in needle valve for cheap. Any links or advice is welcome. Sorry if the post is confusing, I'm so close.....and still so far away to complete.