Motherboard:

Dev-fused devices are sometimes called prototypes in the security research industry. They are essentially phones that have not finished the production process, or have been reverted to a development state.

These rare iPhones have many security features disabled, allowing researchers to probe them much more easily than the iPhones you can buy at a store. Since the Black Hat talk, dev-fused iPhones have become a tool that security researchers around the world use to find previously unknown iPhone vulnerabilities (known as zero days), Motherboard has learned.

Fascinating look at a world few of us know about.