The BPF-B503 from Mini Circuits is a Band Pass Filter with Frequency 495 to 510 MHz, Bandwidth 15 MHz, Center Frequency 503 MHz, Insertion Loss 2.92 to 3.52 dB, Rejection 20 dB @ 440 and 565 MHz. Tags: Surface Mount, Ceramic, Ceramic Filter. More details for BPF-B503 can be seen below.