I actually seen one of these on the road and they're completely useless, you can barely see the laser line on the road and I was right next to the guy! Then when he turned the outside line faded completely away. Also keep in mind that in order for a laser to be bright enough you would need a larger battery and it would only last maybe 15 minutes! I know a guy who alters his pen green laser pointer to the point where he can burn holes through black balloons easily and I think the battery lasts about 15 minutes instead of an hour, now try that with a laser that shoots out 2 beams and in the shape of a line instead of a dot, so in order for that tail light to be able to burn for 2 to 4 hours they had to dim down the laser a lot to the point of uselessness, but with a camera set with the aperture wide open and over exposing the picture it looks like something worthwhile..