The "blue dot" was put in tail lights and head lights so aircraft would be less likely to spot them. After the war they just caught on. In some states blue dot tail lights are not allowed so either get the ones with switched bulb on the blue light or carry some electrical tape. The headlights with the blue dot in them don't matter since headlights are different colors now anyway. I have the blue dot headlights with the blue dot inside and blue dot tail lights. I also have the blue dot stainless visors. I don't know if I'll run the visors but its not like you have to cut your chassis to put them on or off. To each his own IMHO.
