The 7-539 from Chelton is a Low Pass RF Filter with Frequency 30 to 530 MHz, Stopband Frequency 960 to 1220 MHz, Insertion Loss 0.5 dB, Rejection 60 dB, Upper Rejection 60 dB @960 to 1220 MHz. Tags: Module with Connector, Chebyshev Filter. More details for 7-539 can be seen below.