The BL5200K08051T from Frontier Electronics is a Balun with Frequency 4.9 to 5.8 GHz, Amplitude Balance ± 2 dB, Phase Balance 10 Degree, Insertion Loss 1.1 dB, Return Loss 10 dB. Tags: Ceramic, Surface Mount, Unbalanced to Balanced. More details for BL5200K08051T can be seen below.