The mini foldable keyboard is just larger than a credit card, & measures 92 x 71 x 12mm (3.6 x 2.8 x 0.24 inches) when closed, & 176 x 71 x 6mm (6.9 x 2.8 x 0.47 inches) when open & weighs just about 3 ounces. The internal battery provides 9 hours of continuous use or 45hrs of standby time. It can be recharged through a USB cable.
It allows the user to choose between the SPP (Serial Port Profile) mode and the HID (Human Interface Device) mode & the keyboard has 63 individual keys.
"The HID mode allows "Out of the Box" Alphanumeric compatibility with many products, including PCs, Laptops and many PDAs using the HID technology."
It will cost you about $69.95.
[Freedom Mini Duo Keyboard Via Pop Gadget]