Unipolar switches are the most simple Hall-effect device available, with sensing capability in one direction, either the North or South pole of a magnet, for B_OP and B_RP. When using sensors that have a unidirectional sensing direction, proper magnet orientation is required for B-field sensing. Common magnet implementations for Hall-effect switches include alternating North or South orientation magnets, or single orientation magnets spaced far enough apart to allow the B-field to fall below the B_RP threshold between magnets. In digital Hall-effect devices, B_OP and B_RP dictate the switching thresholds for the device. For a Hall-effect switch, this characteristic makes the output duty cycle dependent on the magnetic threshold levels and magnet movement. Generally, more care must be taken to implement Hall-effect switches into a flow meter design compared to latches. However, switches can be used with various magnet implementations, further adding to flexibility in terms of flow meter mechanical design. Figure 2-3 displays the unipolar switch operation.