The FC-4 from Sahajanand Laser Technology Limited is a Microwave Absorber with Absorption 25 to 35 dB, Frequency 8 to 80 GHz, Thickness 4 Inch/101.6 mm, Thickness 4 Inch, Thickness (mm) 101.6 mm. Tags: Foam Absorber. More details for FC-4 can be seen below.