Most scope accessories are attached to a blaster via an tactical or accessory rail, meaning that they can be removed or swapped out based on the user's desires. Compatibility between blasters depends on the type of tactical rail used on a blaster.
To help with the aiming process, scopes have a reticle, crosshair, or another point of reference meant to act as a guide as to where a dart will land when fire. However, this is often not the case, due not only to the way that darts fire, but also the way the scope attachment will sit and align atop the blaster in question. Additionally, due to parallax, the crosshair will not always be set on the same spot depending on how the user sees through the scope, so even if darts flew perfectly straight from the barrel, it would not always land where the crosshair is pointed. As such, scopes are mainly used for cosmetic purposes. However, some scopes such as the Distance Scope use a front and rear reticle meant for lining up like iron sights, in which case parallax would not be much of an issue.
Unlike their real world counterparts, most dart blaster scopes do not feature magnification, with the exception of the NerfDay/Night Zoom Scope (which uses digital zoom rather than telescopic zoom). Many features small plastic inserts that act as if they would function as lenses, although these do not serve any purpose other than for aesthetics.
Red dot sights[]
A red dot sight, pinpoint sight, or reflex sight is an accessory sight similar to a scope, but uses a red LED to project a red dot on the lens. Red dot sights are less common than scopes and are more compact. The position of the dot depends on the angle the sight is viewed from, which allows the dot to stay vaguely on target even when the sight is viewed at a different angle, although parallax is still an issue. Higher quality red dot sights such as ones made for airsoft or real steel use have less parallax and on accurate, high performance blasters, they can actually improve the user's aim.