This is a 14 tooth 1/2" ID drive sprocket that mates with a #25 roller chain (bicycle chain). With a drive sprocket on a motor and an roller chain, you can make things move.

These sprockets are great for adding to the shaft of a motor to make something move. The drive sprocket will pair with a #25 roller chain.

This is the same sprocket that guides #25 chain and drive sprocket

This is the chain that mates with the #25 sprockets.

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.

You can use this mechanism to either help position the roller chain to assist the drive sprocket, or be used as a free wheel for one end of a loop of roller chain.

Single strand steel #40 chain