The best-known of bagpipes are actually one kind of bagpipe, the Great Highland Bagpipe. It has two tenor drones, one bass drone, a blowpipe and a chanter. There are nine holes on the chanter that can be covered and uncovered to create nine notes, embellishments and grace notes are usually played as well. The drones, blowpipe and chanter fit into stocks, cylindrical usually wooden tubes, that are tied into the bag. At the base of the blowpipe is a valve that allows air to flow into the bag but not flow out.