The S3 meter has a single-sided sensor. As such, the magnetic field is thrown off from the face of the sensor in a fountain-like pattern. As conductive material is elevated away from the face of the sensor, the field becomes less and less dense. This causes the sensor to read the material as having a higher and higher sheet resistance. This effect is called “lift-off.” Because of the lift-off effect, a single-sided sensor is only useful if the material elevation is carefully controlled. Elevation can be controlled in multiple ways.