Dam It® stops the dripping that cools and prevents fast soldering. Slip the tool into the copper pipe and tighten the nut to make the seal expand to dam the water. Dam It® remains in an L-shape and does not hinge. Dam It® soldering aid can also be used to sweat off and remove faulty valves that are cooled by dripping water. In addition to individual sizes, a kit #03382 for 1/2" - 1" is available.