Am assuming these are mostly for AL, although their marketing materials show them "welding" copper pipe as well. Technically these are
brazing rods for mostly AL I believe. Some people have had good results, the key being good surface prep (as usual). If you are trying to apply to a corroded surface you cannot clean they will not work for sure. My understanding is that like all brazing, they rely on the microscopic porosity of the base material. When these things were first introduced years ago everyone made fun of them as a gimmick. But they do have their place I think. For mostly esthetic repair and for lower strength cracks, they might be an OK solution. As a point of comparison, some people in reviews claim that
FlexSeal works better...so take that as you may.
Most reviews say they are very messy, and score them both high and low. They seem to be targeted towards materials 1060, 1350, 3003, 3004, 3005, 5005, 5050, 6053, 6061, 6951, 7005 and cast alloys 710.0 and 711.0; they can be used on galvanized steel as well as copper. Supposedly.
There is a video on YouTube of these exact rods being used on a corroded AL boat bottom that cannot be prep'd properly. It doesn't go well. Personally, I think banjo music in the video's background dooms it to failure from the get-go—but then again I still can't watch
Deliverance without doing a safety assessment of the other men in the room before the movie starts.
Please report back your findings if you try them.