The WLJ5-1200-1300-40-5000-300 from Wainwright Instruments is a Low Pass RF Filter with Frequency DC to 1.2 / 1.3 GHz, Stopband Frequency Chosen Fco x 1.53 to 5 GHz, 3 dB Cutoff Frequency Choice of 1.2 to 1.3 GHz, Insertion Loss 0.25 to 0.3 dB, Rejection 40 dB. Tags: Module with Connector, Lumped Component Filter, Chebyshev Filter. More details for WLJ5-1200-1300-40-5000-300 can be seen below.