Notice the very large bore (hole) in the drive sprocket. That bore won't fit any motor generally used in the DIY CNC community, but accompanied with a collar that reduces the bore, now you have a great combination that fits well with 1/4" shafts.
Basic information on sprockets and roller chain. This video explains the uses of drive sprockets and idler sprocket and goes into some details of the geometry of the sprockets, how they work and various configuration that can be used with sprockets and roller chain. Information on calculating the steps per inch is also explained.