So I'm planning on doing a little drilling for my fog lights under the bottom grills but I have a question about the aluminum bar behind the bumper...

I don't have time right now to take the bumper off and check, then put it back on, because I need to drive the car later today but can anyone tell me if the aluminum bar is completely enclosed or if there's an opening behind so that I can reach into it? I can't really explain.. Here's a very crude picture of the cross sections I'm trying to describe:



Picture A or B? Basically, I need to know if I need to drill metal screws in or if I can just drill a hole for a long bolt and fasten it with a nut on the other side. Thanks!

 

its actually two squares back to back. Im pretty sure it is but dont hold me to my memory as its about as good as a 98 year olds memory.