Ferrules are the professional solution to mounting exterior vinyl shutters to stone, river rock, lap siding, uneven brick, or other irregular surfaces. You can even use the ferrules to stabilize the outboard side of the vinyl shutters when mounting them over the top of the window's trim.
Made of a type of styrene, ferrules can be trimmed to the proper length using a hacksaw or PVC pipe cutter. They double as a neat way to cover your exposed mounting hardware when installing vinyl shutters to shingles or shake, and can be painted to make the shutter mounting hardware blend with its environment.
Ferrules will work with either Shutter-Loks or painted screws. They can be used with any brand or style of exterior vinyl shutters for a professionally finished installation.