The MR31-0003-20 from MAST Technologies is a Microwave Absorber with Frequency 8 to 12 GHz, Thickness 0.040”, 1.0mm, Thickness (Inch) 0.040”, Thickness (mm) 1.0mm, Operating Temperature -60 Degrees F to 375 Degrees F. Tags: Surface Wave Absorber. More details for MR31-0003-20 can be seen below.