What Zoom is best for my iPhone 5?

I'm going to a music concert next week so i decided to buy myself a extra zoom for my iPhone 5 on ebay so my pictures will be able to see closer and be more clear instead of buying a camera, but as i have come to buy the zoom it has gave me 2 options, Aluminum Zoom and Optical Zoom. What is the difference and what one would be most suited for me?

Hope you can help, thank you!

Optical zoom is where the lens itself focusses on a distant subject. It's the best type of zoom to use.
However, I've never heard of Aluminium zoom so can't offer any advice on that one. Sorry!

Most camera phones only have digital zoom. Digital zoom does only crops in a section of the whole picture and blows it up, picture quality is degraded, plus its not good if you are just holding the phone, because a small movement in your hand will be a big movement in the video, best to use with a tripod. Digital zoom nor optical zoom will not make your pictures clearer. You may get closer to the subject but you will not gain clarity.

Aluminum is the material they use to make the housing of the Optical zoom lense that you attach to the iphone.

In photography Optical zoom refers to the use of Optical (glass elements) lenses to magnify the subject. You don't loose picture quality when using optical zoom.

It looks like a mini telescope. I highly discourage you from buying that attachment, i really doubt it works well.

I say, just go to the concert and have fun and enjoy.