Here's a link to a double flare kit from Cl***ic Performance Products -- have been very happy with mine. Used it for 3/8 fuel line with no problems. Price was right. http://www.cl***icperform.com/Store/Tools/CPDFTD.htm
I've got a cheap one, been using it for a few years on brakes and fuel stuff, got a snap on one the other day, works heaps better, does a much nicer job.