Dimensions: 1.75-inch diameter
Though the Flora may not be quite so petite, its unique form factor deserves mention. Primarily designed to be used in wearable projects, the Flora has pads that can be accessed via conductive thread. The many accessories for it include peripherals meant to be sewn into wearable apparel, such as LEDs, GPS units, and accelerometers. It is fully Arduino compatable, so all the Arduino libraries and tutorials should work on it.