ok simple it lets you see things that generate heat, like pedestrians, motor on a car etc. It lets you see in the dark or fog and through brush like seeing deer on the side of the road etc.. Its nice to know something is there before you need to know its there. I don't know how practical it would be on a moving truck on the highway unless it was dense fog but its a toy to play with... Technology is getting better and before long you will have a heads up display in the vehicle telling you whats where for several hundred to several thousand feet.