CPU
ATmega328 @ 16MHz (same MCU used in Arduino UNO)
Display
Nokia 5110 84×48 monochrome graphic LCD /w white backlight (adjustable with a built in potentiometer)
Sound
0.5W speaker with 4-channel audio generation, 3.5mm headphone connector, hardware volume control
Input
7 super-clicky pushbuttons with replaceable button caps (D-pad + ABC buttons)
Storage
32kB of FLASH program memory, 2kB of RAM, up to 2GB SD card for loading and saving programs (HEX files) and data (128MB card included)
Communication
serial UART port, i2c, SPI
Power
single cell LiPo, 3.7V, 600mAh, charged with your regular micro USB smartphone charger
Dimensions
approx. 13cm x 6cm x 2.5cm (depending on the casing, hacks, mods, expansions…)