The X4C35K1-04S from TTM Technologies is a Directional Coupler with Frequency 3.1 to 4.2 GHz, Coupling 4 dB, Coupling Variation ±0.40 dB, Average Power 10 W, Insertion Loss 0.25 dB. Tags: Surface Mount. More details for X4C35K1-04S can be seen below.