The OHP 55-4 from Beijing Ocean Microwave Corporation is a RF High Pass Filter with Frequency 55 MHz to 1.25 GHz, Insertion Loss 0.51 to 0.65 dB, Rejection 40 @ 35.5 MHz to 60 @ DC to 28, 9 MHz, VSWR 1.23:1, 1.50:1, Return Loss 14 to 20 dB. Tags: Module with Connectors, Chebyshev. More details for OHP 55-4 can be seen below.