NEW IMPROVED DESIGN. Serrated gripping teeth with spring loaded, self adjusting jaws. Ideal tool for easy adjustment of tie rods other difficult to access parts. Firmly grips all type of fasteners. 1/4″- 1/2″ (5 ? 12mm) range for the 3/8″ drive. Ratcheting action design allows the tool to rotate back and reposition, allowing better performance than regular crowfoot wrenches, especially in tight spaces