A polarization cloak was a sophisticated cloaking device used by Ramuran tracers to hide themselves and their ships. Tracer ships could fire weapons through the cloak, while remaining untargetable themselves. The personal version of a polarization cloak could be disrupted by a magneton sweep. In 2374, the former tracer Kellin modified the USS Voyager sensors to penetrate the Ramuran polarization cloaks, albeit only for a brief time. (VOY: "Unforgettable")