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. (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.