The WVR-821B-5M01 from Wevercomm is a Band Stop Filter with Stopband Frequency 818.5 to 823.5 MHz, Bandwidth 5 MHz, Insertion Loss 1 dB, Rejection 40 dB Min @821MHz, Power 26 W. Tags: Module with Connectors, Cavity Filter, Notch Filter. More details for WVR-821B-5M01 can be seen below.