Simply a Top Case

Positive: Grip
Delivery
Cut-outs for headphones, pen, etc.
Heads for Sound and Power Button
Protection
For me personally, even a plus: the fake screws on the back that the whole design even more harmonious
do

Negatives: When the display accumulates very easily on the edges of dust
When taking out the mobile phone for the first time from the envelope makes you look even care if you do not something
wrecking as it really is very strict

To further examples to name to protect me is times like the cover down once it even with the display forward to a concrete floor and you can see either on the envelope anything not on the phone itself phone 4.