The EMA4D1227P30E30B from ECHO Microwave is a Band Pass Filter with Frequency 1.21 to 1.25 GHz, Insertion Loss 2.5 dB, Rejection 30 to 40 dB, Return Loss 15 dB. Tags: Surface Mount, Ceramic, Ceramic Filter. More details for EMA4D1227P30E30B can be seen below.