Hi Roy. Even though I own about 10 or 15 different filler types just because I am a horder, I don't have any of the high dollar aerospace stuff because I never have a real use for it and I am a tight wad. That said, I know there are charts etc to choose the best or most compatible filler for tig welding, and I am pretty good at choosing what I need and use, but I'll bet some of the newer guys would like to hear/see more on tig filler for steel and aluminum so they can make good choices. For example on aluminum using 4043 would be a bad choice if you are going to get the finished parts anodized so 5356 would be a better choice . . . unless the part is going to be used in an environment on 150 degrees Fahrenheit where 4043 would be the better choice. What option would you use then? Using 4047 has the same issue as 5356. Anyhow, it would be a great subject to see what you professionals do. Take one FMF for Aluminum and another for Steel.