http://www.qtcgears.com/ is where we get our gears from. Just find the type and size that fit your requirements. I forgot what the model number of these were but shouldn't be hard to find. I actually directly mention what PID values i'm using in the video. 0.05 for P, 0.01 for i, and 0.5 for d. the d parameter doesn't really have much effect though.