About this item Including screws and nuts, it is easy to install onto helmet. Including screws and nuts, it is easy to install onto helmet. Nice accessory for your combat helmet, providing much convenience. With it ,you can attach lights, lasers, cameras or other devices to helmet by using standard arc rail dovetail adapter(not included). It can be firmly fixed on your helmet, not easy to drop. Used for Fast helmets or other modified helmet equipment guide rail.