16T Aluminum Timing Pulley With Teeth (16/2GT)

Used in Prusa and most other 3D Printers, used in conjunction with 2GT belts. Aluminum. Has teeth, not much more to say.

If you need one, you need one. This is it.

Buy extras, they wear out.

(Check out that cool idler bearing in the center, moves like a low end idler bearing should.)