These are not your average project gears. Gears are often too expensive, too small, or require hot glue (ow!) to attach to shafts. TeacherGeek project gears are a class of their own. Featuring splined holes to push and rotate with a dowel shaft, they can be easily removed or changed as designs evolve and experiments expand (no hot glue necessary). They transfer impressive amounts of power, while remaining simple enough for elementary use. Whether in our tinker set or as part of a larger STEM, science fair, or engineering project, these gears are a great choice. Gear colors might vary.