The Mouse Blocker Classic has a small red LED light that is very dim when operating correctly. In regular sunlight or inside a shop this light may appear to be out. However, if you view this light when dark by covering with your hands or checking at night you will see the subtle glow from this light. When designing the Mouse Blocker Classic we did not want there to be additional power draw from the battery from a bright light. This is one of the reasons the Mouse Blocker Classic is the industry leader for protecting things for many months on a standard 12 volt battery.