The QTR-HD-31RC Reflectance Sensor is a part of Pololu’s line of QTR (Quantized Time-of-Flight) sensor boards. It integrates 31 separate reflectance sensors into a single board, making it ideal for line following robots or other robotic projects that require a line following capability. This model has a nominal range of 1-10mm and is equipped with fast, digital time-of-flight readouts and integrated infrared emitter timing. It is capable of sampling up to 256 different reflectance levels, and each sensor has a configurable sensitivities, allowing you to adjust the board to optimize its performance to a given application. This module has a built-in temperature compensation, as well as automated power save mode, making it a great choice for applications that require a reliable, yet energy-efficient sensor solution.