Features 2 interface for 5V Servo connected to the high-resolution dedicated timer - no jitter. Can drive 4 DC motors or 2 stepper motors or 2 Servo. Up to 4 bi-directional DC motors with individual 8-bit rate selection. Up to 2 stepper motors (unipolar or bipolar) with single coil, double coil or interleaved stepping. 4 H-Bridges: per bridge provides 0.6A (1.2A current) with thermal protection. L293D is a monolithic integrated, high voltage, high current, 4-channel driver. Basically this means using this chip you can use DC motors and power supplies of up to 36 Volts, thats some pretty big motors and the chip can supply a maximum current of 600mA per channel. The L293D chip is also what's known as a type of H-Bridge. The H-Bridge is typically an electrical circuit that enables a voltage to be applied across a load in either direction to an output, e.g. motor. Features:   Pull down resistors keep motors disabled during power-up. Built In Reset Button. 2 external terminal power interface, for separate logic/motor supplies. Fully compatible for Mega, Diecimila & Duemilanove. Specification: Motor voltage: 4.5V~25V Current: ≤1A PCB size: 6.7*5.3cm / 2.64*2.09in   Package l ist: 1 * Motor Drive Shield Expansion Board Package List