This is a replacement Arrma Differential Gear Set. 
Features:
Super-tough and durable steel to withstand extreme RC action
Precision manufactured Gear Teeth for consistent performance in all conditions
Metal Cross Shafts for long-lasting durability and super-efficient running at high speeds
Includes:
(4) 10T Satellite Gears
(2) Metal Cross Shafts
(2) 20T Planetary Gears
(4) Satellite Gear Shims
(4) Metal Cross Shaft Insert