Fit of the infrared-to-X-ray SEDs characteristic of the B2 1811+31 low and high states with Eq. (7), in blue and red, respectively. The spectral points in the optical/UV range were reconstructed from Swift-UVOT observations, whereas the X-ray ones derive from Swift-XRT data. Infrared points are WISE data. The shaded areas correspond to the 1σ band fit uncertainties, while the best-fit synchrotron peak frequencies and their uncertainties are marked by the vertical solid and dotted lines.