Phillips or flat head screws used on engines, driveline components or other heavy machinery can be notoriously difficult to loosen with your average screwdriver. But the SCA impact screwdriver set will help you free those tight screws with less effort, and no rounding of fasteners. The SCA Impact Screwdriver set is supplied with the manual impact driver, 4x 36mm flat and phillips head bits, and 2x 80mm flat and phillips head bits all contained within a handy metal storage tin. Using the impact driver is simple. Choose the bit which best suits the screw, place it in the tip of the impact driver, and place the tip on the screw to be loosened or tightened. Now turn the body of the impact driver in the direction you wish to move the screw. The bit should stay still and the body will move about a quarter turn before stopping. Apply some rotational force with one hand, and hit the impact driver firmly on the back with a hammer using the other hand. A few hits should see the screw tighten up, or break free for easy removal.