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.
- Drive end chamfer and four detents help provide quick positive engagement with drive tool on any of the socket drive walls
- Tight tolerances for snug fit on fastener
- Large clearance holes, concentric opening and nut end chamfer make it easy to position socket on fasteners
