Cut Off Lever (V7)
The Cut Off lever is an integral part of your AEG's gearbox. This mechanical piece is largely responsible for semi-auto fire, as it effectively disengages the gun from continual fire. As you can imagine this causes the part to wear down over time, which is exacerbated by the fact that in many guns they are constructed out of weak pot-metal.
This aftermarket cut off lever is manufactured by SHS out of steel, which is infinitely more durable. Installing the part requires complete disassembly of the gearbox, and may require some slight modification depending on the brand of gearbox, parts used inside etc.