I normally take off from a plastic lid from my storage crate. It makes checking your gps lock signals easy as you can just look down at the reflection in the plastic lid. Today I was on my own and didn't have the lid with me. I turned my iPhone off and held that under the rear lights and the reflection on that sucker works even better to watch GPS lock signal. Its a very obvious solution but thought I would share as before I thought of it I was struggling to see them in bright sunlight.