Works great if you follow the instructions! Thoroughly clean the surface, heat quickly, once the desired temperature (+750ยฐ < 800ยฐ) is reached, move the rod back and forth or in a circular motion to remove all oxidized aluminum from the weld area. You will see the dark gray molten slag evaporate and begin to turn bright silver. Once that happens, fill in the weld and go. It won't break, it needs to be cut. I used it to weld an entire enclosed aluminum trailer. They work great!