The FLA-309NF-50W from Metropole Products Inc. is a Low Pass RF Filter with Frequency DC to 4 MHz, Stopband Frequency 5.5 MHz, 3 dB Cutoff Frequency 5 MHz, Insertion Loss 0.5 dB, Rejection 40 dB min. for 5.5 MHz. Tags: Module with Connector, Lumped Component Filter. More details for FLA-309NF-50W can be seen below.