Stopends - External or Internal?
Guttering should always project slightly past the end of the roof to ensure that in windy conditions the rain will still fall inside the guttering. The usual way to finish a run of guttering is to bring the gutter past the end of the tiles or slates and then fit an external stopend, which clips directly onto the gutter and forms a watertight, sealed end.
Internal stopends are much less commonly used. An internal stopend has no clips, as it is fitted into another fitting instead - most commonly a running outlet. It is fitted in exactly the same way as a piece of gutter in that it is clipped down onto the rubber seal of the fitting in question to make a watertight joint.
EXTERNAL STOPEND INTERNAL STOPEND