Suggest to add lubricating oil, it can be reduce the friction between the metal gears, also the sound will be smaller when it is running.

Total 4Pcs( 19T 20T 21T 22T )
These 48P gear set fir for 1/8 inch (3.175mm) shaft size Motors,please make sure your RC motor shaft have the same diameter (3.17mm)
Compatible with Tamiya Kyosho RedCat Losi Axial Traxxas 1/8 1/10 RC Car.
The 48 pitch gear set made of aluminum alloy,it is durable for long-lasting performance.
Variety of tooth pinions allows for different racing track conditions.
Comes with set screws for easy installation, make sure the spur gear and pinion gear have the same pitch(32P), otherwise the teeth won't mesh.

Itenm Name: 48P 3.175mm Shaft Motor Gear Set
Material: Steel
Pinion Gear:19T 20T 21T 22T ;
Pinion Gear Hole Inner Diameter:3.17mm
Tooth pitch: 48 pitch;
Height: 9mm

Package List:
1 x 48P 3.175mm 19T Pinion Gear
1 x 48P 3.175mm 20T Pinion Gear
1 x 48P 3.175mm 21T Pinion Gear
1 x 48P 3.175mm 22T Pinion Gear