Uniweld Type17-4 weld / braze tip can be used with acetylene, propane, MAP//Pro, and natural gas. Capable of welding 3/16" of metal, and brazing 1 1/2" of copper. Tip elbow is copper, mixer and nut are brass. Has two O-Ring seals so tip nut only needs to be firmly hand tightened. Tip will fit either the 71 or WH550 welding handle.