Dennis- The tool has a has a large main body the same diameter of your spar bushing (less a few thousandths of an inch for clearance). Extending from that pin is a smaller diameter pin that is offset to the side like a cam. The smaller pin goes in the second spar through the part of the hole you can see. Using the lever handle, the pin is rotated 180 degrees, pulling the bushings into alignment. Assuming the wings are adequately supported, they will remain in alignment when the tool is removed. You can then install the actual steel spar pin.