Wera 6004 Joker Self-Setting Spanner Set. With its continuous and parallel jaws the Joker 6004 replaces several single spanner sizes. The required size is automatically and continuously set when attaching the tool to the hexagon bolt or screw. The integrated lever mechanism securely clamps the hexagon screw or bolt between the jaws which significantly reduces the risk of slippage or damage. The ratchet feature ensures fast and consistent screw driving without removing the tool. By using the corner-width rectangular prisms a return angle of only 30 can be achieved. The single-arm design in conjunction with the ratchet feature and the corner-width prism makes it possible to work even in confined spaces.