The LS-10055-40 from ARC Technologies, Inc. is a Microwave Absorber with Frequency 10 GHz, Insertion Loss -16 dB, Thickness 0.140” ± 0.030”, 3.56mm ±0.76mm, Thickness 0.140” ± 0.030”, Thickness (mm) 3.56mm ±0.76mm. More details for LS-10055-40 can be seen below.