The Dist-A-Line was designed by a surveyor to allow the instrument man to get line and distance in one operation. This is accomplished by having the prism, Gammon reel? and plumb bob string all hang over the point in perfect vertical alignment with the optical center of the prism. There is no level bubble to check or get knocked out of adjustment. The Prism tilts for inclined shots and has a range of approx. +-2000 feet depending on the EDM. Working height is any length of the Gammon reel? string, which can be replaced quickly when worn. The unit is 3/4" x 2" x 5 1/4" and weighs 10oz. It comes with Prism, gammon reel, 18oz plumb bob and a custom made heavy duty leather carrying case.