The Light Collar System is a versatile work aid device used by space station crew to identify and integrate with the station taskmaster AI.  Lately the collars have seen limited planetside export, usually to individual mercenaries or small cells, and sometimes as fashion accessories.
 
The LCS can be easily attached to a jacket with non-damaging clips or screws for a more permanent install.  It can also be worn without attaching to anything.  The LEDs can be set to a large variety of colors with a remote control.  Comes with a battery pack that requires 8xAA batteries (not included).
 
More information on attachment, alternative power supplys, and more is detailed in the manual.