The AM121.5CR164 from Anatech Electronics is a Band Pass Filter with Frequency 121.45 to 121.55 MHz, Bandwidth 0.1 KHz, Center Frequency 121.5 MHz, Insertion Loss 6.0 dB, Upper Rejection 30 dB at Fc +/-130 kHz. Tags: Surface Mount, Crystal Filter. More details for AM121.5CR164 can be seen below.