I bought this to power a Raspberry Pi Model 2B and used fresh Duracell Alkaline batteries. It powers the bare Pi just fine and it takes still pictures using the Pi camera, but I whenever I try to use the camera in video mode or plug in a WiPi dongle, the Pi reboots. Both the video camera and the dongle work fine with the mains power supply, suggesting a problem with voltage drop in the battery case or its cable. Inside the case there's a protection diode and shorting it out with a bare wire allowed my Pi to work almost perfectly. Now the only difference with the mains power supply is that the red LED does not light up when on battery.
In my work, I use a headlamp and loupes for magnification every day. The battery pack for my lamp failed, and it would have cost almost $400 from the manufacturer to replace it. Being the tight-wad that I am, I found this at MCM and it has been a perfect solution (I did have to change the round plug on my light to a USB). Saved a ton of money! I cannot attest to how long this will last having to change batteries every day, but it is reasonably constructed, and seems durable enough. Today, I am buying a few more to have on hand in case this product should be discontinued or disappear. For the price, you can't go wrong!
Very very good website! Reliable and delivered exactly on the day they gave me. Easily recommended!