Barb is 1/4″. 1/4″ or 5/16″ beverage tubing is recommended for gas line.
Tip N’ Trick: Sometimes ball lock fittings are a challenge to quick disconnect “on and off” a cornelius keg. We recommend spraying the body connect on the keg first with a sanitizer solution which acts as a lubricant. When applying the ball lock fitting to the body connect, give a twist and turn to make it easier to connect.