rubee has no reflections and is not blocked by steel or liquids and therefore is volumetric (not line-of-sight). that makes rubee robust in harsh environment visibility and security applications. it also means rubee has no tempest target or eavesdropping risks in secure facilities. rubee is the only wireless technology to ever be approved for use in secure facilities by the u.s. department of energy (doe). rubee has also been approved by doe and hero tests by the dod for use in high explosive areas with a safe separation distance (ssd) of zero. rubee is also only wireless technology to ever be approved by doe with an intrinsic safety zero ssd. rubee tags may be detected with high sensitivity through doors, even if the asset is hidden in steel brief case, as well as in vehicles though gates using antennas buried in a road.