The BD4859N5050AHF from Anaren Inc is a Balun with Frequency 4.8 to 5.9 GHz, Amplitude Balance ± 1.2 dB, Phase Balance 7 Degree, Insertion Loss 0.7 dB, Power 1 W. Tags: Surface Mount, Unbalanced to Balanced. More details for BD4859N5050AHF can be seen below.