Proto Tools is an American industrial hand tool company. Founded as Plomb, it is presently a division of Stanley Black & Decker. The company is credited with creating the first combination wrench in 1933.
- Use extensions to gain access to fasteners in locations that would otherwise be difficult to reach.
- Male square is oriented in line with female squares for use with fixed head torque wrenches.
- Full chamfer at drive opening (when applicable) for easy engagement with drive tools.
