Product Description

Stepper motor driver for Arduino UNO CNC Shield or eg. Polulus. Heat sink included.

Facts.
PCB size: 15 x 20 mm
PCB color: red
Sensor resistance: 0.1 Ohm

Data:
http://reprap.org/wiki/StepStick
Calculation for reference voltage for a 0.8 Ampere stepper motor
Vref = 0.8A x 8 x 0.1 = 0.640V is 100 percent.
If the stepper motor goes 100 percent, it will get hot and need to be cooled.
70% can be recommended, so 0.7 * 0.640V = 0.448 Volt