https://www.vice.com/en_us/article/jgxm3g/crossbow-imsi-catcher-new-stingray

Multiple federal agencies and parts of the military have purchased a surveillance device called a 'Crossbow,' an upgrade to the well-known Stingray brand of IMSI-catchers which appears to target 4G devices, according to procurement records reviewed by Motherboard.

The devices are made by Harris, which also makes Stingrays. Stingrays and IMSI-catchers in general are designed to track cellphones. The finding comes after the American Civil Liberties Union (ACLU) published documents last month showing that Immigration and Customs Enforcement (ICE) had previously purchased the Crossbow devices. Now, Motherboard has found other federal Crossbow purchasers and more information about its capabilities.