Battery & 2 Types Of ATT Cases

I have a couple of questions about a few accessories I just looked up at the ATT website. The first question I have is about this "Naked Shell Case", which can be found here; http://www.wireless.att.com/cell-phone-service/cell-phone-details/?device=Samsung+Impression+(a877)+-+Blue&q_sku=sku3680237. I know this one isn't like the snap one cases that they also offer, but then how do you put it on? They also say that it comes with a built-in screen protector, how did they manage that? What material is this? And does it come with a clip? If anyone has this or has seen this personally please answer my questions.

The next question I have is about a battery that they have also listed in the same link above. It does not say that it is a replacement battery and the description says that it has a little extra power but I don't know if they actually mean that. Is this battery the same as one already in our phones? "Standard Li-Ion 1000 mA Battery".

I have that casemate shell.  It's just a clear acrylic shell that has a built in screen protector.

Personally I don't like it very much, it makes the phone too bulky but it does seem to provide very good protection from drops or scratches.  Like all plastic/acrylic cases dust and "stuff" does slip between the phone and the case you have to clean it frequently if you don't want it to look bad, or scratch the phone.

Alright thanks, I tried the clip on before but took it off right away after I seen it push my phone apart a bit, I wanted to know if the shell was any different.

I had that exact case and like KennyStang it gets real dirty under the case and your always cleaning it...not to mention the fact that the clear case scratches easy itself. So it ends up looking like sh!t after awhile.