Isokinetic cannon
From Memory Alpha, the free Star Trek reference
The isokinetic cannon is a type of anti-starship projectile weapon sold by the Entharans. The isokinetic cannon is capable of penetrating a chromoelectric force field and ten meters of solid monotanium with a single hit. In 2374, the USS Voyager negotiated with the Entharan arms dealer Kovin to purchase an isokinetic cannon for the price of astrometric charts spanning 12 sectors as well as 125 isolinear chips with an additional 5 chips for installation supervision. (VOY: "Retrospect")
The cannon was in the process of being installed, but it is not clear whether Voyager retained it since it was never seen again.
