The Model A-4 Multiple Point Rod Extensometer with Snap-Ring Anchors is quickly and easily installed in boreholes in hard or competent rock. Anchors are pushed to the required depth on the end of setting rods and then a cord is pulled to remove the locking pin which allows two retaining rings on each anchor to snap outward and grip the borehole. Up to eight anchors can be installed, at various depths, in a 76 mm diameter borehole. Particularly useful in upward directed boreholes.
Specifications
| Standard Range | up to 300 mm nominal |
| Least Reading | 0.025 mm |
| Borehole Diameter¹ | 38 mm to 76 mm |
| Maximum Length | 50 m |
¹Any borehole diameter up to 76 mm may be specified. Note that the size of the borehole required increases with the addition of more measuring points.
