The SR50A is a rugged acoustic sensor for measuring the distance from the sensor to a target. This sensor is typically used for snow depth or water depth measurements, but it is well-suited for other uses. Because the speed of sound in air varies with temperature, an independent temperature measurement is required to compensate the distance reading. A simple calculation is applied to initial readings for this purpose. Note: Campbell Scientific recommends model SR50A-316SS-L for marine environments.