Patent ID: 8695460

Claim:
A wrench comprising: an elongate handle having a first driving head connected to a first end thereof and a clamping hole defined through the first driving head, an opening defined through the first driving head and communicating with the clamping hole so as to form two jaws with the opening located between the two jaws which are symmetric relative to each other, the first driving head having a top surface and a bottom surface, the top and bottom surfaces being parallel to a horizontal plane, the top and bottom surfaces being C-shaped surfaces and located along the clamping hole, multiple protrusions extending from an inside of the clamping hole and located about an axis of the clamping hole, a first outer periphery of the top surface being tangent to an inside of a first circle, a second outer periphery of the bottom surface located on a second circle, a diameter of the first circle being larger than a diameter of the second circle, the diameter of the second circle being larger than a diameter of the clamping hole, when the first and second circles are projected on the horizontal plane, the second circle is located within the first circle and is tangent to the second first circle at a tangent point which is located close to a front end of the first driving head, a shortest distance being defined between two respective centers of the first and second circles, the clamping hole and the first circle located on a common axis which is located on a vertical plane, the two respective centers of the first and second circles and the tangent point located on the vertical plane, the two jaws being symmetric relative to the vertical plane.