Chromatte is a 'retro-reflective' fabric designed to serve as a background for use in chroma key production for film, television and video.
This light-weight, flexible fabric contains millions of glass beads that behave like 'cats eyes' - it is dark grey to the eye in ambient light, but when used with a camera mounted LED LiteRing the grey is seen by the camera as a brilliant but more importantly 'even' blue or green background for easy chroma keying.