What is the Best Iphone 5 screen protector that won't make screen dark?

Hi, I'm looking for any good screen protectors for a iphone 5 that will not make the screen dark ( I've seen many protector that make the screen very dark when they are put on ). If anyone has any good ones leave a name of the product and where I can find this product, thanks!

I bought a case on eBay with built in screen protector, it's clear plastic hardly noticible