CST/Berger 54-135K is a 20X Econo Line Level Kit. This kit has non-strip focus knob which prevents breakage and lens damage. This kit is built-in sunshade reduces glare. It has large achromatic coated objective lens for a sharp image. This kit has rubber eyepiece cap protects eyeglasses. It also has durable brass leveling screws. Econo Line instruments, like the 54-135K Line Level Kit, have no circles or vertical arc.