20Pcs Worm Gears, 21x2x3.7mm/0.83×0.08×0.15′(ODxIDxT)402A 0.5Modulus Plastic Gear, White High Rotating Speed Wide Uses for Pulley Belt Shaft Robot RC Motor Worm Crown Hand DIY Car Kit

About This Product :

• Modle: Plastic Gears ; Number of teeth:40 ; Modulus: 0.5 Modulus.
• Outer diameter:21mm; Hole diameter: 2mm.
• 100% Brand new and high quality. Good accessories for Vehicle or remote control, Provides a convenient choice for your DIY project.
• Plastic Gears suit for a science DIY project such as rc model car, model electric robot and displaying how gear ratios work, and any other family small motor DIY project.
• This is the most complete gear set. It can meet your DIY needs.