The 2820-3.8 from KR Electronics (A Division of NIC) is a Band Pass Filter with Frequency 1.8 to 5.8 MHz, Bandwidth 4 MHz, Center Frequency 3.8 MHz, Insertion Loss 3 dB, Rejection 60 dB. Tags: PCB Mount, Surface Mount, Lumped Component Filter. More details for 2820-3.8 can be seen below.