Agent 18 Eco iPhone Shield
Agent 18's Eco iPhone Shield, available in matte black, is split into top and bottom pieces; you slide these sections over the top and bottom of your iPhone, respectively, and they click together in the middle. The case is a snug fit, but still comes off easily when you want it to. Like all Agent 18 iPod and iPhone cases, the bottom of the Eco Shield is flush with the bottom of the iPhone, letting you use bottom-mounted dock-connector accessories; Agent 18 also includes a dock insert, sized specifically for an Eco Shield-encased iPhone, for Apple's Universal dock design, allowing you to use your iPhone with dock-cradle accessories without having to remove the case.
What's unique about the Eco Shield--and what gives the case its name--is that Agent 18 has made it out of "eco-friendly material with minimum carbon impact"--read: recycled plastic--and packaged it using a reasonably-small amount of fully-recyclable plastic and paper. As someone who sees a heartbreaking amount of waste when it comes to the production and packaging of iPod accessories, I applaud Agent 18 for these efforts.
One minor drawback of the Eco Shield is that because the case fits snugly and has no lining, you need to be careful, before putting the case on your iPhone, that both the phone and the interior of the case are clean. Harder pieces of dirt or dust can scuff your iPhone while you're sliding it in and out of the case.
(Note that the Eco Shield has a small notch on the top and one on each side near the bottom. It appears these three notches provide places for a holster or belt clip to attach; however, Agent 18 doesn't currently sell such an accessory.)