z-axis calibration tool for p3 steel prusa

This is a practical tool that I have invented to equalize the heights of both Z rods. place the tool like I did in the picture and get the upper x-axis rod under the tool. At this point, power off the printer or the motors. Then if the upper x-bar touches both sides of the tool, its OK. If not, turn the rods in order that the upper x-bar touches both sides of the tool.