Chroniton torpedo

Chroniton torpedoes were destructive projectile weapons used by the Krenim Imperium. These torpedoes were based on temporal science, and existed in a constant state of temporal flux. This allowed them to pass unhindered through the shields of enemy ships. The torpedoes had individual temporal variences, an example of which was one torpedo which had a variance of 1.47 milliseconds. (VOY: "Before and After", "Year of Hell")

In an alternate timeline, in 2374 Seven of Nine and Tuvok developed temporal shields which counteracted the effects of chroniton torpedoes. (VOY: "Year of Hell")

In another timeline, the crew of the Voyager defeated the advantage of the torpedoes by recalibrating the targeting scanners to a parametric frequency, disabling the torpedo launches before they fired. (VOY: "Before and After")