The MR21-0005-20 from MAST Technologies is a Microwave Absorber with Frequency 5 to 9 GHz, Thickness 0.06 Inch/1.5 mm, Thickness 0.06 Inch, Thickness (mm) 1.5 mm, Operating Temperature -60 Degrees F to 375 Degrees F. Tags: Cavity Resonance Absorber. More details for MR21-0005-20 can be seen below.