I have these two welding sticks for personal use. My youngest son reclined in one of my dining room chairs and the key came loose. Needless to say, he rolled over, but he was agile and strong enough to avoid injury. Inspection of the weld revealed a bead of wire that had not been set hot enough to penetrate the thickest element of the joint. I tested the new weld by rocking my back with the baby on my lap.