Perfect fit for the top of my CR-10S Z axis. Assemble the horizontal and vertical guides of the rod, but you should only assemble the inner part 2 so that the parts with the gear nuts are straight and hold the protruding parts of the rod. Then do the second, then the outer end. That way it keeps all the parts right. You need to hold down the two sides to make sure they line up perfectly with the horizontal and vertical tabs. A bit of work, but you only have to do it once!