As very high electric fields correspond to only tiny changes in the width of the crystal, this width can be changed with better-than- μm precision, making piezo crystals the most important tool for positioning objects with extreme accuracy—thus their use in actuators. Multilayer ceramics, using layers thinner than 100 μm, allow reaching high electric fields with voltage lower than 150 V. These ceramics are used within two kinds of actuators: direct piezo actuators and amplified piezoelectric actuators. While direct actuator's stroke is generally lower than 100 μm, amplified piezo actuators can reach millimeter strokes.