Hop-Stopper is OffRoadOnlys solution to the Wrangelr JK hood flutter. This part is manufactured of stainless steel and assembles below the steel tube structure of the grill that the hood hook catches on when the hood is opened. When the hood is closed, the hood hook passes through the Hop-Stopper and then simply pushing the lever to the closed position, the hood hook is retained solidly below the grille tube structure and the hood is now 100% retained, no movement at all! The Hop-Stopper is engaged by reaching through the middle grill slot, but it is mounted high enough that you canÍt see it from the front of the vehicle. You need to reach in and feel it to know its there.