Microcontroller board based on the ATmega2560. The green board is a step further than the yellow for your larger project needs, like 3D printers and robotics.
It has 54 digital input/output pins (up to 12 can be used as PWM outputs and up to 16 as analog inputs), a 16MHz clock, a USB connection, TWI, SPI, UART interfaces, a power jack, an ICSP header, and a reset button. Fully Arduino® compatible.
The board has all you need to get started, just plug in a USB cable or an AC/DC adapter and play!