All FullFields have a one-piece main tube and eyepiece, the steel-on-steel adjustment system, and HiLume multi-coatings on every single air to glass lens surface. The FullField II is even more forgiving for eye position, is a little shorter, and a good bit lighter. The magnification ring and eyepiece have been made into one solid unit requiring only two seals rather than three. We still use special quad seals rather than O-rings so each potential leak path is double-sealed by design. To change magnification, simply turn the entire eyepiece.