Driving head for open wrench

An open wrench comprising:

• a handle and a first driving head connected to a first end of the handle, the first driving head having a U-shaped body which has a mounting hole defined therein and an opening communicates with the mounting hole, each of top surface and bottom surface of the first driving head having a first face and a second face, a height of the second face being higher than that of the first face, the first and second faces being parallel to a horizontal plane, the second face being a U-shaped face and located along with the mounting hole, the first face being a U-shaped face and located outside of the second face, an area of the second face being ⅓ to ⅔ of an area of the first area, a U-shaped groove defined between the first and second faces, a first distance defined between the two respective second faces of the top surface and the bottom surface of the first driving head, the handle having a central axis, a mediate point defined between two insides of the mounting hole, the mounting hole having an axial axis which passes through the mediate point and is parallel to the horizontal plane, an angle of degrees defined between the axial axis and the central axis, the handle having a first surface, a second surface, a third surface and a fourth surface, the first and third surfaces being wider than the second and fourth surfaces, a second driving head connected to a second end of the handle, the second driving head extending an angle relative to the first surface, the handle having maximum width at a middle section thereof and a width being gradually reduced toward the first and second ends of the handle.