HMC5883L - 3 Axis Magnetometer
The HMC5883L is a 3 Axis Magnetometer made by Honeywell. It has a high-resolution HMC118X series magneto-resistive sensor with an ASIC and a 12 bit ADC. It uses I2C for communicating with other devices. It can be used as an eCompass and for other uses like robot navigation.
For a detailed look at the specifications, refer to the datasheet: https://cdn-shop.adafruit.com/datasheets/HMC5883L_3-Axis_Digital_Compass_IC.pdf