Old Man Screw Knockers are known by many different names, ”Old Man”, ”Screw Knocker”, and ”Woodpecker”. Old Man Screw Knockers are an extractor that gets results by loosening or removing stubborn, corroded, or over tightened screws and other fasteners. They feature a 0.401 shank that fits into a rivet gun which delivers a high paced pulse that breaks hardware free without damaging the surrounding materials. Old Man Screw Knockers accept a 3/8” drive bit holder that is not included.