I buy this bucking for all my AEGs.
After 1000 rouds, you will gain more precision and more constant trajectory.
I use it with AEG under 350fps. If you are over 380-400fps use the black one.
The only one cons that I think, it's too soft so when I disassemble my hop up, I deform the bucking ...
But if you have well assembled, that's rules !