Our Cold Weather Exit Sign with Red Letters is the perfect UL924 compliant battery backup fixture for outdoor and indoor areas which feature cold temperatures. The "IH" in the SKU stands for "Internal Heater". This refers to the thermostatic battery heater that the unit comes with, which allows it to fully operate in environments that feature temperatures as low as -4º Fahrenheit.ConstructionThe WLEX-R-BB-IH is constructed with a corrosion resistant plastic housing with a light gray finish. A clear polycarbonate faceplate protects the sign legend and keeps it clear of dust, liquid and debris. A silicone gasket creates a watertight seal between the housing and lens, qualifying this fixtures UL Wet Location listing.This Cold Weather Exit Sign with Red Letters includes a Red 'EXIT' stencil, and comes standard in single-sided configuration. The red stencil includes knockout directional chevrons (arrows), adaptable to any exit strategy. The WLEX-G-BB-IH does not include mounting brackets.BatteryThe WLEX-R-BB-IH model includes a maintenance-free, Nickel Cadmium (Ni-Cd) battery pack. It provides emergency backup power to the exit sign for at least 90 minutes, and only requires 24-hours to fully recharge. Ni-Cd is the longest lasting battery type available, lasting an average of 15 years.A push-to-test switch and LED pilot light on the side of the exit sign housing allows you to test the emergency readiness of the fixture. The LED will flash if any fault is detected in the circuit, LED light strip or battery.