The EMA4C2900P20F35B from ECHO Microwave is a Band Pass Filter with Frequency 2.89 to 2.91 GHz, Insertion Loss 3 dB, Rejection 35 dB @ 2390 to 2410 MHz, Return Loss 15 dB. Tags: Surface Mount, Ceramic, Ceramic Filter. More details for EMA4C2900P20F35B can be seen below.