3/8" Dr. Universal Stud Extractor Fits 3/8" impact wrench or ratcheting wrench, The impact wrench can be inserted directly into the stud extractor. The stud extractor is adjustable to fit studs that are anywhere from 1/4" to 1/2" (6-12mm) Ideal for removing stripped, rusted or broken studs. Hex drive can be used with an impact wrench, ratcheting wrench or regular wrench