Sanguinololu Rev 1.3a The board is designed to be flexible in the user"s power source availability, allowing for an ATX power supply to power the board, or the user can choose to install the voltage regulator kit for use with any power supply 7V-30V.The board features a developer friendly expansion port supporting I2C, SPI, UART, as well as a few ADC pins. All 14 expansion pins can be used as GPIO as well. A4988 driver This product is a carrier board or breakout board for Allegro"s A4988 DMOS Microstepping Driver with Translator and Overcurrent Protection by Pololu; we therefore recommend careful reading of the A4988 datasheet before using this product. This stepper motor driver lets you control one bipolar stepper motor at up to 2 A output current per coil. Opto Endstop 3D The optical endstop is a reliable endstop / switch solution for any type of 3D printers and other CNC and/ or 3D tools. Package Content 1 x Sanguinololu Rev 1.3a 4 x A4988 stepper driver 3 x Mechanical Endstop Please contact our customer service for the instructions & code.