The FNP-1521 from Filtronetics is a Low Pass RF Filter with Frequency DC to 20000 MHz, Bandwidth 20000 MHz, Stopband Frequency 25 to 40 GHz, 3 dB Cutoff Frequency 20000 MHz, Insertion Loss 1.0 dB. Tags: Module with Connector, Cavity Filter. More details for FNP-1521 can be seen below.