This is a 78-piece Gears Assorted Kit for Do-It-Yourself Robotics and Household Repair. The Gear Package contains a spindle, single/double crown gear, pulley, rack, bevel gear, copper gear, bushings, axles, wheels, rubber bands, and other accessories for DIY toy cars/robots/motors.
These gears can be used for a variety of tasks, including toy repair, DIY science and small prototypes, product design, and mechanical modeling.
The majority of gear has a 2mm aperture (tight or loose), with 2.3mm and 3.17mm holes in addition to the two-spindle hole. It contains worm gears, crown gears, and a few other gears that are suitable for DIY model production technology.
These tools are used in laboratories, science education, DIY models and RC-airplane/helicopter repair, and many household repairs such as old music systems, among other things. It's an excellent toolkit for promoting DIY abilities, and also improving children's hands-on skill, and encouraging innovative thinking.