The MR21-0002-20 from MAST Technologies is a Microwave Absorber with Frequency 13 to 17 GHz, Thickness 0.030 Inch/0.8 mm, Thickness 0.030 Inch, Thickness (mm) 0.8 mm, Operating Temperature -60 Degrees F to 375 Degrees F. Tags: Cavity Resonance Absorber. More details for MR21-0002-20 can be seen below.