Looks like it's your basic 3/16" ID 5/16" OD picnic tap line. The barb is probably a 1/4" barb so a tight fit but works well. Hope that helps.

From Kegland au com the "Bronco / Picnic Party Tap" has a 6mm barb. Smaller that the ones I've bought from MB. It fits their 5mm ID Beer line. They sell a EVABarrier 5mm(13/64) x 8mm(5/16) Double Wall EVA beer line. I assume this is what comes with the Drafto Kit. The line looks smaller than than MB draft lines. On another note. The regulator connector is just a coupler. It does not have a "back flow" device. Meaning you cannot pressurize one can and move the regulator to another can without losing pressure in the first can. Hope this helps.

Mine is 1/4 inch MPT to 1/4 inch flare. Paste this into A****n and it should pull one up:Litorange 4 PCS Metals Brass Couples Tube Fitting Half Union Gas Adapter 1/4" Flare x 1/4 Inch NPT Male Pipe Connector