One end has a female W21.8 thread for connecting to a CO2 gas bottle and the other end has female G5/8 thread for connecting to an argon regulator. CO2 BOTTLE TO ARGON REGULATOR ADAPTER. If you have an Argon regulator and want to connect to a CO2 gas bottle then you can use this adapter to make it fit, saves thecost of having 2 regulators.
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