The BSF-435MS1 from RF ONE Electronics is a Band Stop Filter with Stopband Frequency 0.4 to 0.47 GHz, Insertion Loss 3 dB, Rejection 40 dB, Power 50 W, Return Loss 8 dB. Tags: Module with Connectors, Cavity Filter, Ceramic Filter, LC Filter. More details for BSF-435MS1 can be seen below.