Abstract: A modified horizontal strain indicator. Two spaced cap assemblies joined by a tensioned music wire are mounted on different roof bolts within a mine. One of the assemblies is the anchor cap assembly and the other assembly of the pair is the measuring cap assembly. The anchor assembly consists of two tubular sections vertically mounted upon each other and adjustably rotatable with respect to each other. The lower section thereof has an adjustable wire tensioning device to hold one end of the wire. Similarly the measuring cap assembly has two tubular sections which are vertically mounted on each other and also adjustably rotatable with respect to each other. Its lower section has a plunger biasing mechanism to tension the wire. Both upper sections of the anchor and measuring assembly may use set screws to vertically mount the invention to a mine roof on their respective rock bolts. A removable gage can be used to read the wire's horizontal displacement when attached to the plunger biasing mechanism.