用途：适用于平行四边形法、异长法观测弛度，可将经纬仪固定于铁塔角钢上。uses:to observe the sagging by means of the parallelogram method and different length method .can mount the theodolite on the pylon □ 放大倍数 magnification factor：4 □ 适用角铁applicable angle iron：∠56～125 □ 重量weight(kg)：1.6
