Recent examples include models that shoot pepper spray, serve as health monitors, and double as game controllers. The Raspberry Pi-based NVC (Night Vision Camera) case, however, has its own trick up its sleeve – it lets the iPhone 6 see in the dark.
Another is to get the FLIR ONE case, which is handier than the adapters because it's always with the phone – just like the NVC. It utilizes thermal imaging technology, in which even very small amounts of heat emitted by objects (including inanimate ones) is amplified and used to create an image.
The NVC takes a simpler approach, which is reflected in its lower price. It uses eight infrared LEDs to illuminate subjects up to 30 feet (9 m) away. That light isn't visible to the human eye, but it is to the 720p infrared camera built into the case.