... 3, multi-role catalogue 4,liner error compensation dro digital readout:function 1:zero clearing 2:reset 3:mm/inch ... scale and rotary encoderadvantage:1,the high precision digital readout is specialization design,elegant appearance ,high speed of numeation,multy function2, ... wear-resisiting,good shield.3,independent power,widely used,high stabilization,capacity of resisting disturbance well4, the power ...