... but if those are the ones which don't cut the flame immediately when you let go of the trigger, to me they'd be useless. Depends on the use perhaps, but I find the Rothenberger badged ones (made by a US company) hot enough for plumbing. 35mm pipe is easy even with normal propane gas and a small burner. Mapp gas and the standard (bigger) burner is just about ok for small brazing jobs.