How should I describe this part which looks like a small gear so that I can research replacements?
This came with my FLSUN 3D printer, which may be based on a Prusa design.
3D Printing Stack Exchange is a question and answer site for 3D printing enthusiasts. It only takes a minute to sign up.Sign up to join this community
This is a timing belt pulley.
Specifically, is a GT2 timing pulley, 2 mm pitch (between teeth), 6 mm wide. The drive diameter is measured by the number of teeth (16 in this case) , the shaft diameter (bore) is measured in mm.
The 'GT2' part refers to the tooth profile, some other examples are shown half way down this page.
It is an "aluminum timing pulley"