Their description:
Product Description
Seidio’s Innocase Holster Combo includes the Innocase II and Innocase Holster. Crafted from a hard yet flexible material, the Innocase II provides an amazingly thin layer of protection without adding the excessive bulk of other cases. It consists of interlocking top and bottom pieces that fit your phone snugly, and Seidio’s signature soft touch finish provides a great feel and better grip without attracting lint. The Innocase Holster is based on the same design as S… More >>
Go & get it here - i can recommend it:
Seidio Innocase II Surface Spring Clip Holster Combo for iPhone 3G, 3G S

Does not come out & gathers lint, interferes with signal reception
I bought this case for my iPhone 3GS. While it fits the iphone pretty well and looks decent, it is impossible to remove the bottom piece of the case (or get the entire case out of the iphone once it is on). Also this case attracts all the lint from the pockets of your trousers - the iPhone without the cover practically attracts none.
I noticed that my phone and gps reception drop with the cover than without.
In a nutshell - poor design and materials - avoid at all costs.
The case fits perfectly and looks great.
The belt clip draws attention to my hips, which my full-length mirror suggests is my most handsome feature.
I strongly recommend this case and clip for anyone with an iphone and handsome hips.
Well the part of the case that covers the phone is great! I definitely would recommend it. For some reason though the holster part of the combo did not fit my phone once the case was on it.
I just received this case and wanted to give my review. I looked online for a long time in order to find a case which had a spring clip holster as well.
This one is extremely low profile and seems very high quality. The price is high, but its a better deal than paying 30 for clip and 30 for case, as is available from manufacturer.
I would highly recommend this case.
I got this case because Seidio makes awesome blackberry cases. It’s thin, it’s light, it doesn’t get in the way. I also got the belt clip, because I like not putting my phone in my pocket. The problem with this case is that, for some reason, it was designed to go face-in only. Now, when I get my email, I have to pry my phone out of my clip, and check my email, and then awkwardly put it back in the clip. It’s not an elegant solution.
I know the face-in is supposed to protect your screen, etc., but what’s the point of that if it renders your phone completely unusable? It should have been designed to go in either way. It sucks that I dropped [...] on 3 of them - only to go back to the flimsier griffin clip with no protective shell.