EMA-11 measuring anchor, also known as rock bolt extensometer, is used to determine load exerted on rock bolts. It is a precision instrument designed to evaluate anchor system forces and their distribution within the length of the bolt and hence its safety and effectiveness.
 
A digital caliper/micrometer depth gage with a resolution of 0.01 mm is used to take readings. An electrical head assembly consisting of four potentiometric sensors is optionally available for electrical output.