It comes packaged with the Tri-Strike.
The Mega Dart Barrel Extension is a small blaster that doubles as a barrel extension. While the name may suggest that the barrel extension itself works on Mega Dart blasters, it cannot be equipped to any, nor is the diameter of the barrel large enough to accommodate a Mega Dart's size (despite the barrel's outer appearance). The Mega Dart portion instead refers to the underbarrel blaster, which fires Mega Darts.
It features the use of an intelligent air restrictor system, which allows for a single dart to be fired from any of the four lower barrels when it is not fully loaded.
Reloading and firing
To reload the Mega Dart Barrel Extension, load up to four Mega Darts into its lower barrels.
Push the priming slide forward and pull back all the way to fire a dart.