Road Sign,Street Sign,Warning Sign,Stop Sign,Parking Sign,No Enter Sign,Speed Limit Sign,Arrow Sign...with LEDs or Not.Solar Sign Alert Systems any sign can be a Sign Alert! Our Sign Alert Systems are solar-powered for energy efficiency and designed to increase road safety by increasing motorist visibility. With Sign Alert’s ultra-bright LEDs, drivers are cautioned in advanced of dangerous highway hazards. Our smart controller allows your sign alert systems to preserve energy and battery life with its auto-dimming feature while maintaining brightness.