Standard keg product (beer) line is 3/16". Almost everything we carry comes with barbs that fit this size beer line. In order to get the tubing onto the barb it is often necessary to dip the end of the tubing in boiling water for a few moments in order to loosen the vinyl and make it more pliable. Be sure to use hose clamps to lock everything down or your lines may blow off and pour beer all over your floor.
Standard gas line is 5/16". All of our gas line connections are built for that size. Be sure to use hose clamps to tighten everything down or you may lose all the gas in your CO2 tank overnight.