The 2037-1 from KR Electronics (A Division of NIC) is a Band Pass Filter with Frequency 19.2 to 20.8 kHz, Bandwidth 1.6 KHz, Center Frequency 20 kHz, Insertion Loss 3 dB, Rejection 90 dB. Tags: PCB Mount, Surface Mount, Lumped Component Filter. More details for 2037-1 can be seen below.