The KDDI Fx0 is the most powerful smartphone on the market, though its hardware is still a few notches down from rival flagship devices running Android or iOS. KDDI, a Japanese carrier, offers the phone only in Japan and gives it an appropriate lock screen. The phone has a 4.7-inch 1,280x720-pixel screen and 1.2GHz quad-core Qualcomm Snapdragon 400 processor.
It's fun to look at the electronics lurking inside the The KDDI Fx0's transparent housing. It's reminiscent of Apple's first-generation iMac design.
The KDDI Fx0's home button features an understated Firefox logo. Developers haven't supported Firefox OS as much as some would like, but there are a number of apps. Those that run on the Web already, such as Microsoft's Outlook.com, are easiest to bring to Firefox OS.
The front-facing camera has a 2.1-megapixel sensor. This lock-screen wallpaper, which rotates into different orientations, makes it awfully hard to read the time and date.
One the right side of the KDDI Fx0 is the power switch. The phone has 16GB of storage.
The KDDI Fx0 comes with an 8-megapixel rear-facing camera and an LED flash. Just beneath it in this photo is the SIM card slot.
Firefox OS uses Nokia's Here Maps app for location and navigation purposes.
On the bottom of the The KDDI Fx0 is a USB charging port and a microphone.
Under reflective light, the stippled pattern on the back of the KDDI Fx0 is very visible, as is the LG Electronics logo on the battery. The South Korean company builds the phone.
The left side of the The KDDI Fx0 shows a volume rocker and Fx0 brand name.
Firefox OS's control panel looks like just about any other you'd see on a smartphone.