A tool includes a handle including a pivotal end, a holding end held by the user in use of the tool and a plurality of teeth formed on an outer periphery of the pivotal end. A first working head includes a pivotal end coupled to the pivotal end of the handle pivotally, a working end engaged with a work piece desired to be driven and an aperture between the pivotal end of the first working head and the working end. A positioning unit includes a positioning plate and an elastic element received in the aperture, with the positioning plate hooking the first working head and pressing the elastic element of the positioning unit respectively. A restricted portion protrudes from the positioning plate between two ends of the positioning plate toward the pivotal end of the handle.  Link to USPTO.