ZKBY-2/3 of roof separation instrument, roof graticule dynamic instrument, roof separation indicator 
 Also known as multi-point displacement meter (balanced, straight bar) 
 The roof separation instrument is for a detection of movement of the roof strata monitoring instruments. It can display the abscission layer of the roof strata within the length of rock bolt and bolt with outside circumstances. Mine engineering and technical personnel, and monitoring staff to determine the length of the bolt, tensile strength, understanding of the bolt used in a reasonable, economic and scientific basis. So as to effectively prevent the roof to collapse and accidents, to ensure mine safety and production. 
 Roof separation device is mainly composed of basis points anchor, strand, sleeve, cursors, tighten the screws. Technical characteristics 
 Reflective color display of the measurement 
 Measurement points (a) 2/3 
 Maximum range (mm) 200 
 Reading accuracy (mm) 
 Installation of the anchor hole diameter (mm) 28-42