KY-82 Roof dynamic instrument KY-82-type instrument is Mine roof dynamic instrument for measuring changes in rock displacement measuring the amount of roof and floor closer, closer to the pace, were stope to pressure prediction, detection abutment pressure peak position value, etc., is an essential tool stope underground pressure observation. Second, the main parameters: Parameter range Minimum height measurement instrument readings crude read full scale parameter value 1.0 ~ 3.0m 0 ~ 200mm 0.01mm of error of less than 1 200mm