The ZBV, developed by American Science and Engineering (AS&E), uses only backscatter imaging in an effort to optimize detection of weapons, explosives, and drugs. Backscatter imaging, as compared to X-ray, transpires when X-rays bounce off of the scanned objects. ZBV sends out X-rays toward a target, and the resulting "scattered" radiation is then translated into black-and-white type images. ZBV's use varies from seizures of large quantities of drugs and detection of bulk explosives to stowaways. Effective results have been reported with the use of ZBV, which provides powerful contraband detection in a mobile unit, with over 400 sales in 46 countries, and deemed an advantageous tactic for law enforcement.