The ECS-21K7.5B from ECS Inc. International is a Band Pass Filter with Frequency 21.396 to 21.403 MHz, Bandwidth 3.75 kHz, Center Frequency 21.4 MHz, Insertion Loss 2.5 dB, Rejection 90 dB. Tags: Through Hole, Crystal Filter. More details for ECS-21K7.5B can be seen below.