The B028RF2S from Knowles is a Band Pass Filter with Frequency 2 to 4 GHz, Bandwidth 2000 MHz, Center Frequency 3000 MHz, Insertion Loss 2.5 to 3.0 dB, Rejection DC to 1.25 GHz (40 dB), 4.85 to 6 GHz (40 dB). Tags: PCB Mount, Ceramic, Ceramic Filter. More details for B028RF2S can be seen below.