The 910x family is a piezoelectric (PE) sensor series for force measurement in the z-direction. These ring force transducers contain a quartz sensor element which measures the force directly transferred to the quartz element located within the sensor. When subjected to a mechanical load, quartz produces an electric charge that is proportional to that load. An outstanding property of quartz is the very low threshold, resulting in a high sensor sensitivity which is extremely linear over the entire measuring range. Thus the behaviour in a certain measuring range is practically identical for all PE sensors, independent of their size. The force sensors are thoroughly tested, but are delivered without calibration certificate and must be calibrated on site after installation.