TIP-II slit-reconstructed images for both days of observation. From top to bottom: continuum, Si i line core intensity, He i line core intensity (red component) and Si i Stokes V. The FOV was different on July 3 and July 5. We provide the dashed rectangles to show the approximate common area of the filament on both days. Characters a) − d) indicate the position of the Stokes profiles presented in Fig. 7. The white arrows point to high concentrations of helium with elongated shapes (thread-like structures).