If you're doing g-mix, you need a cylinder, a nitrogen regulator, and a stout faucet. One word of caution, my gas supplier wouldn't fill anything but the large gas cylinders with g-mix (the ones that bars and restaurants use...about five feet tall). They also wouldn't fill it unless it had the CGA580 connector. I know that's not the case for everyone, but it's worth asking your gas supplier to make sure they're willing to fill one of your existing cylinders.