The 4000BP15U1800 from Johanson Technology is a Band Pass Filter with Frequency 3.1 to 4.9 GHz, Bandwidth 1800 MHz, Center Frequency 4000 MHz, Insertion Loss 2 dB, Rejection 13 to 25 dB. Tags: Surface Mount, Ceramic Filter. More details for 4000BP15U1800 can be seen below.