The 3039 from KR Electronics (A Division of NIC) is a Low Pass RF Filter with Frequency DC to 25.5 MHz, Stopband Frequency 35 MHz, 3 dB Cutoff Frequency 25.5 MHz, Lower Rejection 49 dB@35 MHz, Upper Rejection 1 dB@35 MHz. Tags: Module with Connector. More details for 3039 can be seen below.