The OHP 550-4 from Beijing Ocean Microwave Corporation is a RF High Pass Filter with Frequency 550 MHz to 3 GHz, Insertion Loss 0.42 to 0.45 dB, Rejection 40 @ 355 MHz to 60 @ DC to 289 MHz, VSWR 1.23:1, 1.50:1, Return Loss 14 to 20 dB. Tags: Module with Connectors, Chebyshev. More details for OHP 550-4 can be seen below.