The 20825 3665-4165 from Microwave Filter Company is a Waveguide Filter with Frequency 3.665 to 4.165 GHz, Insertion Loss 0.6 to 0.66 dB, Rejection 45 to 90 dB, Rejection Frequency 3.465 to 4.365 GHz. Tags: Band Pass. More details for 20825 3665-4165 can be seen below.