From the product description, check product page for current description, price and availability:

This brass fitting will convert your C02 tank valve into a valve with a permanent sealing O ring. No more need to buy fiber or plastic tank sealing washers.

Installs in any CGA-320 C02 valve that has female threads in the center of the outlet. Use a 5/32″ hex key to screw this in.

Important: Before ordering, check to see if the C02 valve’s outlet hole on your cylinder has female threads. If it does this will work, if the hole is smooth without threads, this will not fit.

From HBF: Make sure the components you use are compatible and rated for your intended application.  Contact manufacturer with questions about suitability or a specific application.  Always read and follow manufacturer directions.

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