Upgraded gear sets can increase performance and durability of airsoft guns. Gear sets come in different ratios. The lower the ratio, the faster rate of fire. Higher gear set ratios are ideal for high velocity airsoft guns. Gear sets are one of the main drivetrain parts in a gearbox and would increase durability of a gearbox if upgraded. AEG gear sets come in 3 major categories: ‧High Speed to increase ROF of AEG. ‧Standard Ratio with the same ratio as the stock AEG. High Torque with ratio higher than stock ratio to push stronger spring.