... 1, without prism200 meters500 meters, traffic signs, a single prism5 kilometers, meet the different users of the various ... functions, storing50000data, automatically record the angle, distance, coordinates, station and other data;6, unique user key function customization, commonly ... 1degrees 30 ' the most short distance1.5mrange of measurement : single prism (in good weather ) BTS-812R ----3.0KM ...