This is a Comparator based LM393 Linear Hall Effect Sensor Module. This Module is based on S49E linear hall effect sensor. Using this module you can get digital as well as linear output.
This module can be used to detect the presence of a magnetic field. If there is a magnetic field present, it will report a high-level signal. It can be used in many applications such as RPM sensor (for counting the number of shaft revolutions), Robot speed and distance measurements, door switch and robot arm position sensor. Generally, it can be used for any magnetic field detection.