Inlet gas fittings are 16.5 mm flare fittings on track motor, In USA standard fitting size are usually 9/16 18. right hand {oxygen} 9/16 18 left hand thread {acetylene}. and trying to reason with seller is like talking to wall.So my choice was to recut to 9/16 left and right thread{already had right hand die, $ 40 for left hand die}or could remove fittings from your hoses and install nut from supplied barb and nut fittings. bard is like 5/16 {to large for 1/4 in hose. For most i would try this 1st, only because very difficult to start die and keep straight.although i was successful with die threading method.As for unit, works great!! once you do above procedure.