"For accurate visibility measurement","Sensors designed for a variety of visibility measurement applications, including: road weather, waterway visibility measurement, and wind turbine applications such as obstruction light control.","Features  • Robust and versatile  • Accurate measurement of visibility","Key Benefits"," • ​Accurate and traceable   • PWD sensors use the proven forward-scatter measurement principle to measure meteorological optical range (MOR).  • Easy installation   • All Vaisala's PWD sensors are compact (less than one meter long), light-weight, and come with a cable and connector for easy installation, which can be mounted in multiple ways on any existing mast.  • PWD20W - ideal for wind turbine applications   • The challenging conditions on top of a wind turbine require a robust and reliable device like the Visibility Sensor PWD20W, which cost-effectively supports obstruction light control and a range of other wind applications."