The L185XF4S from Knowles is a Low Pass RF Filter with Frequency DC to 18 GHz, Stopband Frequency 20.5 to 40 GHz, 3 dB Cutoff Frequency 18.5 GHz, Insertion Loss 2.2 dB, Rejection 25 dB. Tags: Surface Mount, Ceramic Filter. More details for L185XF4S can be seen below.