Cast Iron Notts Ogee Gutter Right Hand Stopend - 115mm Primed
External Stopends are used to cap off the gutter at the end of the run. The are called external because they fit over the outside of the gutter profile. Because ogee is not a symmetrical system, stop ends are handed either right or left - the video below clarifies the difference.
To prevent the end of the gutter from sagging down you should always support a stopend by fixing a fascia bracket within 150mm of the stopend.