The 2157-51.75-5-50 from KR Electronics (A Division of NIC) is a Band Pass Filter with Frequency 50.455 to 53.045 MHz, Bandwidth 2.59 MHz, Center Frequency 51.75 MHz, Insertion Loss 1 dB, Rejection 40 dB. Tags: DIP, Lumped Component Filter. More details for 2157-51.75-5-50 can be seen below.