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.

Compatible with Arrma 1/8 Typhon 6s , Kraton 6s , Outcast 6s , Notorious 6s , 1/7 6s Fireteam , Mojave (Notice: Not compatible with 1/7 1/8 Arrma 3S 550 vehicle).
Made of high quality metal,it is durable for long-lasting performance..
Good machining made less rough and less noise than other pinions that make them roll smoothly.
Easy to install and upgrade your rc car.

Item Name: Spur Gear & Pinion Gear
Material: Metal
Total Weight:98g/Set
Main Gear:50T
Pinion Gear: 16T 18T 20T ;
Main Gear hole inner diameter:5mm;
Pinion Gear Hole Inner Diameter:5mm

Motor Gear Height: Approx. 15mm
Main Gear Height: Approx. 11mm

50T Main Gear Diameter: Approx. 51.5mm
16T Diameter: Approx. 17.5mm
18T Diameter: Approx.20mm
20T Diameter: Approx.22mm

Package List:
1 x 50T Spur Gear
1 x 16T Motor Gear
1 x 18T Motor Gear
1 x 20T Motor Gear
3× Grub Screws