The EMA4D4050P300C15D from ECHO Microwave is a Band Pass Filter with Frequency 3.9 to 4.2 GHz, Insertion Loss 1.5 dB, Rejection 15 to 40 dB, Return Loss 14 dB. Tags: Surface Mount, Ceramic, Ceramic Filter. More details for EMA4D4050P300C15D can be seen below.