Features: The RAMPS 1.4 board is designed to fit the entire electronics needed for a RepRap in one small package for low cost. RAMPS interfaces an Mega with the powerful MEGA platform and has plenty room for expansion. Additionally, a number of expansion boards can be added to the system as long as the main RAMPS board is kept to the top of the stack. Mega is a micro-controller development board itself has 54 groups digital I / O input / output terminal (14 groups do PWM outputs), 16 sets of simulation than the input side, group 4 UARTs (hardware serial ports), using the 16 MHz crystal oscillator. With the boot-loader, download the program directly via USB without having to go through other external writer. Development IDE interface is based on open-source principles, allows you to free download for use in project work, school teaching, motor control, interactive works. A4988 driver is a carrier board or breakout board for Allegro's A4988 DMOS micro-stepping driver with translator and Over current Protection by Pololu; This stepper motor driver lets you control one bipolar stepper motor at up to 2 A output current per coil. Specifications: RAMPS 1.4 Size: 9.1 x 5.9cm / 3.58 x 2.32" Board for R3 Size: 10.8 x 5.5cm / 4.25 x 2.16" A4988 Color: Green A4988 Quantity: 5pcs Package Includes: 1 x RAMPS 1.4 Board 1 x Board for R3 5 x Soldered A4988 Drivers 5 x Heat Sinks 1 x USB Cable 15 x Jumpers .