The OHP 325-4 from Beijing Ocean Microwave Corporation is a RF High Pass Filter with Frequency 325 MHz to 3 GHz, Insertion Loss 0.38 to 0.4 dB, Rejection 40 @ 210 MHz to 60 @ DC to 171 MHz, VSWR 1.23:1, 1.50:1, Return Loss 14 to 20 dB. Tags: Module with Connectors, Chebyshev. More details for OHP 325-4 can be seen below.