Abstract: An open end wrench includes a handle; and a spaced pair of jaws secured to and projecting from the handle, one of the jaws comprising a first engagement surface and a second engagement surface together arranged in an angled pair, and the other of the jaws comprising a third engagement surface, a fourth engagement surface spaced from the third engagement surface, and a concave surface between the third engagement surface and the fourth engagement surface, the third engagement surface being not parallel to the fourth engagement surface. The second engagement surface extends at an angle between 2-degree and 7-degree with respect to a virtual center line passing an opening between the pair of jaws. The fourth engagement surface extends at an angle between 2-degree and 5-degree with respect to the virtual center line. The second engagement surface is not parallel to the fourth engagement surface.