The 4000BL14U100 from Johanson Technology is a Balun with Frequency 3.1 to 4.8 GHz, Amplitude Balance 1.5 dB, Phase Balance 20 Degree, Insertion Loss 1.2 dB, Power 3 W. Tags: Ceramic, Surface Mount, Unbalanced to Balanced. More details for 4000BL14U100 can be seen below.