The 2921 from KR Electronics (A Division of NIC) is a Low Pass RF Filter with Frequency DC to 118 MHz, Stopband Frequency 126 MHz, 3 dB Cutoff Frequency 118 MHz, Lower Rejection 40 dB@126 MHz, Upper Rejection 2.5 dB@126 MHz. Tags: Module with Connector. More details for 2921 can be seen below.