The Godox Barndoor Kit for AD400Pro Outdoor Flash contains a 4-way barndoor set, honeycomb grid, and one each, green, blue, red, and yellow filter. The barndoors allow you to light areas of the subject you want to and keep light from areas that you don’t want illuminated. The grid narrows the beam spread into a soft-edged circle which is ideal for uses like hair lighting. The color filters are provided for creative expression.