Patent for wrench. Machine bolts have a cylindrical or round shank and therefore in order to remove the nut it is often necessary to employ two tools, one engaged with the head of the bolt to prevent its turning and the other engaged with the nut for removing the same. This invention involves a structure provided which includes a member for engaging and holding the head of the bolt and another member for engaging the nut and capable of being revolved whereby the nut may be screwed on to or unscrewed from the bolt.