ECCOSORB FS is a low-cost solid flat-sheet foam absorber, which is available in various thicknesses and conductivities.  Basically it is a uniform carbon-impregnated flexible foam material, which can be easily glued together to suit various locations and applications.  The NRL suffix refers to its compliance with the fire retardancy requirements of the U.S.  Naval Research Laboratory (NRL) test 8093.

Typically ECCOSORB FS is used in Antenna, RCS and EW anechoic chambers to cover corners (see below) and difficult to cover areas.  The optimal layout depends on the precise chamber dimensions and test configuration.