The Mayhew Tools 2-pc Shake 'N Break Socket Adapter Set, No. 32029, contains two pneumatic bolt breakers. When used with an air hammer, these tools provide the shock and vibration necessary in removing stubborn or frozen fasteners, the company says. These tools are fitted with a standard 0.401 Parker Shank to fit most air guns, and the other end of each tool has either a 1/2" or 3/8" square drive for use with most impact sockets. The built-in hex on the shaft of the tool is used in conjunction with a wrench to assist loosening a stubborn fastener. These tools are 100 percent made in the USA and backed by a lifetime warranty.