The FLP-1800 from Marki Microwave is a Low Pass RF Filter with Frequency DC to 17 GHz, Stopband Frequency 20.5 to 21.75 GHz, 3 dB Cutoff Frequency 18 GHz, Insertion Loss 1.2 dB, Rejection 25 to 50 dB. Tags: Module with Connector. More details for FLP-1800 can be seen below.