Sharpshooter Dart are a type of Nerf ammunition designed specifically to be used with the Sharpshooter.
It was the very first type of dart ammunition released, preceding the Micro Dart and Mega Dart, both of which took major styling cues from Sharpshooter Darts. The Sharpshooter Dart is a yellow Mega Dart with a red suction cup, and fins on the sides of the shaft, which can probably easily get torn. A similar design was done with the later Airtech Jet Squadron Jet, although that type of dart was based off of the standard Micro Dart and is designed after a fighter plane. The Sharpshooter was later re-released without the Sharpshooter Dart, and instead, standard Mega Darts, as the Sharpshooter Dart was discontinued.
Because of the overall design of these darts, especially with the fins, they have something of a resemblance to Target Master Arrows.
The refill pack refers to them as 'Suction Cup Arrows', which is possibly a reference to how they're built more akin to arrows than actual darts. The hold for the barrel post to go in only goes so far before stopping like an Arrow, whereas in an actual dart the hole goes all the way to the dart head. Thus, Sharpshooter Darts are technically a type of arrow even smaller than the Gear Tooth Arrow.