http://www.chiefdelphi.com/forums/sh...ad.php?t=51472
Please search before you post. The question has likely already been answered at least once.
Note that you will have to drill the holes in most sprockets that you buy. Neither InnovationFIRST nor AndyMark sell the exact same sprockets that are in the kit of parts.
http://andymark.biz/gearssprockets.html
http://www.ifirobotics.com/sprockets.shtml