Axial SB profiles of UGC 7321 at 3.6 μm (first panel), grz combined mean (second panel), NUV (third panel), and FUV (fourth panel), along with the NUV-[grz] (fifth panel) and the NUV-[3.6] (sixth panel) colours. The radial profiles are shown for the thin disk (in blue), the thick disk (in red), and the entire disk (black). For consistency with Comerón et al. (2018), the analysis is limited to their outermost fitted point. The inset plots display the same radial profiles for the MW-type NGC 4565 (see also Martínez-Lombilla et al. 2019). The vertical dashed lines indicate the truncation loci in the 3.6 μm images.