The outer dimensions of the Fiber Tensile Module are 80 x 100 x 22 mm³, it is mounted to the SEM or light microscope specimen stage "like a large specimen". It allows in-situ observation of tensile testing experiments at extremely low forces, yet very high load resolution (down to 1×10^-5 N). The tensile speed range is 0,1 to 20 µm/s. These features, coupled with maximum stiffness of this substage, allow very accurate measurements on fibers of down to 2.5 µm diameter, and several millimeters length. The specimens can be observed statically or dynamically at magnifications well beyond 10 000 x in daily routine work.

The load is measured by the principle of frequency variations on a spring-loaded metal wire. The displacement is taken by a differential transformer (LVDT).

The enlarged view shows the specimen holder, which is a pair of ceramic tubes, ground down to half their diameter (red tips). One side is attached to a parallel sled, driven by a combination of DC-tacho-motor/angular encoder for precise recognition of the displacement. A fine tungsten wire touches the specimen from underneath at 90 degrees. This wire allows heating up the specimen locally.