In this 1 minute short video the worker butt splices the ends of two rebars with a jig that holds the two ends squarely together. He puts a cup around the joint and fills the cup with some kind of flux. He then connects the welding electrode and adjusts the jig so the ends make contact and heat up. After a few seconds the weld is complete and he removes the electrode, cup and jig and goes to the next weld.