yeah you can still see the brakes and back up lights just fine, i mean they aren't as bright as before but you can still see them. i was wondering that too but i figured might as well try it. its only like 8 bucks for a can and you hardly use any. i'm thinking about doing the marker lights on the front fenders. as you can see on the right side taillight in the sun you can see through the tint. but when using the spray on tint you have to sand the lights down with 400 grit sandpaper and put light coats on otherwise it'll run. and its very easy to get this stuff to run.