This signal light is easy to install using a common 4 inch round body cutout with Amp Sure Seal Connectors to ensure a tight seal. Using only LED technology provides you high quality lighting. Our advanced internal optics technology disperses a wider angle of light maximizing LED power and a UV stabilized lens prevents fading. These are a great fit for DOT Construction Vehicles, Commercial Vehicle Trailers, Transit Buses, Shuttle Buses & School Bus applications.