I have BSE on my 8310. It covers ALL of the of the plastic, none of the rubber. It comes in 6 pieces; screen, back, sides (2), 2 pieces for area around mic./battery lock. The only place that isn't covered is the space between keys.
It fits great. I'm VERY pleased with it. I think that's why they call it BEST.
The other thing is that without the skin, smudges would be EVERYWHERE on the plastic. With the BSE, they're greatly minimized, if not eliminated. The only choice as far as I'm concerned.