This adapter was specifically designed to provide 5.25V not 5V, but we still call it a 5V USB adapter. We did this on purpose to solve a problem that occurs often with USB-powered gadgets: they draw so much current than the resistance of the cable causes a voltage drop, so instead of 5V, the device sees 4.75V or so. To avoid this problem, we made the adapter 5.25V. This is because the USB power specification allows up to 5.25V, and its safe for all 5V electronics, and has the benefit of making up for any loss due to thin USB cables. Basically, you can use it where ever USB 5V power is needed, with no risk of damage, and it will happily work at the full current range, no matter what cable you use!
The adapter does not have a cable, instead there is a USB 'A' type port on the bottom, where you can plug any USB cable in. The data lines have resistors on them, to match what is inside of an 'Apple iPhone' type charger, and we tested this adapter successfully with an iPhone 4 so it ought to work with anything that can charge with an iPhone adapter.
This adapter is great for use with an Arduino, Raspberry Pi, teensy, NETduino, etc.! Also good with our Lithium-polymer battery chargers, so you can just carry a USB cable.
This particular adapter is very nice, with a red indicator LED to let you know its working!