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