The 2371 from KR Electronics (A Division of NIC) is a Low Pass RF Filter with Frequency DC to 4 MHz, Stopband Frequency 17.5 MHz, 3 dB Cutoff Frequency 4 MHz, Lower Rejection 50 [email protected] MHz, Upper Rejection 3 [email protected] MHz. Tags: Plug In. More details for 2371 can be seen below.