One 1/8 NPT threaded port for versatile connections to standard regulators or hoses. Fits 21*4 CO2 tank thread, enabling compatibility with common CO2 cylinders. Compact and lightweight design for easy handling, transport, and storage. Easy to screw an empty CO2 cylinder into the adapter, simplifying cylinder setup and replacement. Professionally manufactured with accuracy, durable, and not easy to break. Anticorrosion and wearresistant for long service life. Use scenarios Field or workshop CO2 cylinder changes: quickly connect the adapter to an empty cylinder with 21*4 thread and link to a regulator via the 1/8 NPT port for recharging or testing. DIY and prototyping: convenient, compact connection for CO2 supply in small projects that require a reliable 1/8 NPT interface and 21*4 tank compatibility. Spare or backup accessory: keep in your toolbox to ensure fast cylinder swaps in CO2powered setups that use 21*4 threaded tanks.