"I understand trying to keep the cost and complexity down, but I think Vans should have at least offered this as an option. It is a simple Matco valve, that allows normal brake action, but when you pull a knob on the panel, and then push on the brakes, the check valve in this gizmo locks the brakes on. To carry chocks all the time and get out and chock the plane at each stop to keep it from rolling away seems like something I don't want to do. This fixes the problem, another great reason to go EAB instead of ELSA."