For reference, consider a Nightforce NXS and a USO SN-3 TPAL with illumination. The Nightforce incorporates parallax, windage, and illumination in a small section of the central main tube (the saddle), and the USO uses a large part of the central main tube to accomplish the same thing with extra knobs. What are the internal mechanical designs of each of these scopes that account for the different physical implementations?