This is a replacement nipple that attaches to the side of your regulator which then attaches to your CO2 tank that has a CGA 320 Valve.
It has 1/4" NPT right hand threading which attaches to your CO2 regulator, and the other end will fit on your standard CGA 320 CO2 tank valve.
You may also need a replacement CO2 Tank Regulator Nut to secuore this nipple to your CO2.
These nipple need to be used with a CO2 Regulator Washer to seal correctly.