The 2506 from KR Electronics (A Division of NIC) is a Low Pass RF Filter with Frequency DC to 15 MHz, Stopband Frequency 59.25 MHz, 3 dB Cutoff Frequency 15 MHz, Lower Rejection 50 [email protected] MHz, Upper Rejection 0.1 [email protected] MHz. Tags: Plug In. More details for 2506 can be seen below.