Oregon Scientific UVN800 Ultra-Violet Index Sensor is compatible with the WMR88A, WMR80, WMR90A, WMR100 and WMR200 professional weather stations. It collects UV data and records a risk message that indicates when it was noted. It has a transmission range of up to 330 feet (100 meters) and is wall mountable or stake mountable. For longer life and use in colder climates, Oregon recommends Lithium batteries. Standard Alkaline batteries contain significant amounts of water. Because of this they will freeze in low temperatures of approximately 10 F (-12 C). Consumer grade Lithium batteries have a much lower threshold for temperature with an estimated freezing range of below -22 F (-30 C). Collects UV data UV Index readings and risk message: Low, Moderate, High, Very High, and Extremely High Compatible with Oregon Scientific wireless weather stations. See sensors and Accessories for compatibility Transmission range up to 330 feet (100 meters) unobstructed Transmission frequency: every 73 seconds Outdoor temperature range -4 F to 140 F (-20 C to 60 C) Wall mount or stake apparatus for insertion into the ground RF frequency transmits at 433MHz Requires 2 AA batteries (not included)