Man, is the Diff case a neat little iPhone case. It starts out as a tough case with a tripod mount (Zzzzz) but quickly picks up thanks to a clever cover and a pro-level lens mount.
Yes, lens mount. The lens hole in the Diff has a bayonet fixing, so its accessory lenses can be quickly twisted and snapped into place. Compare this to clip-on or magnetic lenses, which need you to line them up by eye every time you use them. The Diff be bought with a set of three lenses: a 2-in-1 macro/wide-angle and a fisheye. These lenses are so ubiquitous across various product lines that I suspect that they are all just rebadged and rejigged lenses from the same factory.
A nice youch is that you can use your existing lenses by buying the Diff converters for them.
The case itself is clever, too. The front has a hard flap which protects the screen, and can also flip up to be used as a shade when shooting in sunny weather. There is another version which also has a kickstand at the back, and that kickstand can also double as a credit card pocket.
Finally, a big hole in the tripod mount can be used to hang the whole lot from a carabiner.
The prices are good too. The cases go for $35 each, the lenses at $50 per set and the adapters are just $6 for a set of two.