After applying ridge vent to a home, some attics are over vented. Most people say cover or block the gable vent, but if the ceiling below are vaulted, the air is too slow to reach the attic, if it does. To solve this problem, we have been using decorative gable vent covers. The covers are only 1" thick to snap over the old vent (in many different styles). If the attic cools good after the ridge vent, we use a vented cover to cut down on moisture in the attic. If the vent needs cut off, we use a non vented cover to block everything. No more trying to match aged siding or paint.