Craftsman Hand Impact Driver, 3/8-Inch Set (Cmmt14104).

Designed to convert the force of a hammer blow into 200 foot pounds of torque, the Impact Tool Set loosens frozen fasteners quickly and easily. By using the included bit set, the hand impact driver can be used to both loosen and tighten Philips and slotted fasteners, as well as drive 3/8-inch sockets.