Qunqi L293D Motor Drive Shield for Arduino Duemilanove Mega UNO R3 AVR ATMEL 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 12 Volts 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. 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. Can drive 4 DC motors or 2 stepper motors or 2 Servo.