Amazon.com: UpGLeuch 117PCS Technic Gears and Axles Sets for Lego Technic Sets,Technic Parts and Pieces Bulk Building Block Accessories-Technic Replacement Connectors, Axles, Gears and Gears Rack, Worm, Pins : Toys & Games
Upgrade Your LEGO® Builds with LEGO® Part 94925 - Technic, Gear 16 Tooth (Second Version - Reinforced)
Lego® Technic 32198 Gear Wheel 20 Teeth (tan)
LEGO Technic Gear or Axle SET MINDSTORMS SPIKE Prime, EV3 Robotic, lot pack | eBay