The 2391A-8-50 from KR Electronics (A Division of NIC) is a Low Pass RF Filter with Frequency DC to 8 MHz, Stopband Frequency 11.04 MHz, 3 dB Cutoff Frequency 8 MHz, Lower Rejection 45 [email protected] MHz, Upper Rejection 0.25 [email protected] MHz. Tags: Module with Connector. More details for 2391A-8-50 can be seen below.