The HD31331 from HD Communications Corp is a Band Pass Filter with Frequency 321.5 to 328.5 MHz, Center Frequency 325 MHz, Insertion Loss 3 to 4 dB, Rejection 50 to 60 dB, Upper Rejection 50 to 60 dB @ 370MHz. Tags: Module with Connectors, RF SAW Filter. More details for HD31331 can be seen below.