full exertion of the clamping force by the overcenter linkage or alternatively may be operated to slightly retract the jaws 4 and 6 while allowing the handle 3 to be in substantially the same position thereby with the alternative operation of the lever 5 the wrench 1 may be employed as a box wrench without exertion of the clamping force by the jaws in gripping a fastener of course the lever 5 serves to facilitate opening the handle 3 from the housing 2 since by releasing the forces exerted by the overcenter linkage the handle 3 is readily moved to the open position the lever 5 is supported within apertures 22 and 23 fig2 a in the sidewall of the housing 2 the apertures 22 and 23 being located for positioning the lever 5 alongside the forward end of the link 9 and bottom side of handle 3 the lever 5 fig5 comprises a cam 24 formed of a flat shaped mid portion of the lever there being a stub shaft 25 of smaller diameter and a stub shaft 26 of larger diameter extending from opposite ends of the cam 24 the shaft 25 rests within the aperture 22 and shaft 26 rests within the aperture 23 the aperture 23 being larger than the aperture 22 to accommodate the difference in shaft diameter a thumb grip 27 extends from the larger stub shaft 26 perpendicularly to the common axis of rotation of the shafts 25 26 whereby the lever 5 is rotated with rotation of the lever 5 its cam 24 can position the link.