The 3650-40-ML from Holland Shielding Systems is a Microwave Absorber with Absorption 18 to 23 dB, Frequency 1 to 18 GHz, Thickness 1.57 Inch/40 mm, Thickness 1.57 Inch, Thickness (mm) 40 mm. Tags: Foam Absorber. More details for 3650-40-ML can be seen below.