The WLJ9-300-400-40-3000-100 from Wainwright Instruments is a Low Pass RF Filter with Frequency DC to 300 / 400 MHz, Stopband Frequency Chosen Fco x 1.125 to 3 GHz, 3 dB Cutoff Frequency Choice of 300 to 400 MHz, Insertion Loss 0.65 to 1 dB, Rejection 40 dB. Tags: Module with Connector, Lumped Component Filter, Chebyshev Filter. More details for WLJ9-300-400-40-3000-100 can be seen below.