I wonder what the "sprocket" in this image is called, since I cannot find anything like it when I searching for sprocket in an online shop like www.grainger.com or globalindustrial.com.
Is there a specific definition for it?
I am unsure if you are looking for a general term, or a description of the actual sprocket in the picture.
The one in the picture is a rear sprocket , specifically a 428 sprocket, a 48T (tooth) 4-bolt rear sprocket for a small motorcycle or moped, possibly a Honda Passport. 428 refers to the specifications of the chain required for the sprocket design.