Been using the Smooth Stop since its introduction.On the original valves it took setting the servo arm to the plunger exactely per instructions.It gave us true proportional brakes on our jets.Now with the new plunger,you don't have to be as precise on the setup as the original.Also it uses very little air to operate and maintenence is very low on what your getting in return.The only thing that really wears out is the 3 o'rings which I change yearly for maintenence.If something fails in the Electronic valves,it usually means a new valve.