Review on CQRobot Ocean 6V 3W 26RPM 32 Oz and 12V 6W 52RPM 63 Motor: Efficient Power and Rotation for Deep-Sea Adventures by Paul Wilson

Like all CQRobot products, this one is well documented. Go to their awesome wiki, search for the SKU "CQR37D" and you can find all sorts of information about it and some code examples to use with Arduino. This is a really good engine with lots of torque. It works very well and is much better documented than most engines I've built in the past. Like most CQRobot products I would highly recommend it - it's a good brand with reliable parts.