1,With water-proof cases, the main part has the excellent sealed for all kinds of field work in any weather. 2,The metal suspension tapes and advanced pneumatic damper make the compensator more adaptable against vibrations ,jolts, shocks and any environmental changes. 3,The advanced structure supply the friction-braked rotation , and endless horizontal drive with a knob at each side. 4,Horizontal circle can be readout 1?or 1gon directly . 0.3m is the shortest focusing for measurement in confined spaces.