Articulation is the foundation for most streamers, it's what gives the inherent swimming action that you'll see in most flies. Additionally, it also helps create flies that are longer than those tied on a single hook. Articulated streamers may be 3" long with a single articulation, or 7" long with multiple articulations. The most common platform is two hooks with one single articulation, but flies like Game Changers can have anywhere from 3-7 articulations! Typically, the more articulations a fly has, the more "swim" it will have.