I recently borrowed my friend's National 8M to see if I wanted to buy it. I really like the flame- I'm sold! Although she had 2 tips for it I've just used the larger one which has 29 ports. Not sure which it is, but it's surface mix. I played with a little boro on it, it seemed to melt pretty fast. I've not tried it with heavy wall tubing though. I really like the fact that I can make larger beads without worrying that one end will get too cold. I am sure the flame probably changes depending on your pressure settings, but mine is a nice radiantly hot bushy flame. It can get very focused with an oxidizing flame, but the flame is cooler then. I prefer bushier flames anyway. It's quite a torch for the $$!
Hope this helps.
Kelly
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