The CBFU4U42255B from Cernex Inc is a Band Pass Filter with Frequency 441 to 449 MHz, Bandwidth 8 MHz, Insertion Loss 2.2 dB, Upper Rejection 55 dB at 490MHz, Lower Rejection 60 dB at 400MHz. Tags: Helical Resonator Filter. More details for CBFU4U42255B can be seen below.