Metal 24T Tooth Gear compatible with Lego Technic like 3648 / 24505 – Dark Ice Designs
Gears: Types of Gears – The Moment Makers
Amazon.com: LEGO Technic Gears Assortment Pack : Toys & Games
Amazon.com: KonHaovF 116PCS Gear and Axle Set for Technic Parts Compatible with with Major Brand Technic Parts, DIY Gears Assortment Pack(Gears Pins Axles Differential New) for Technic Building Blocks Set : Toys