The 21000 3735-4200 from Microwave Filter Company is a Waveguide Filter with Frequency 3.735 to 4.2 GHz, Insertion Loss 0.55 to 0.6 dB, Rejection 45 to 85 dB, Rejection Frequency 3.535 to 4.45 GHz. Tags: Band Pass. More details for 21000 3735-4200 can be seen below.