The origin of the knee in the all-particle spectrum of CRs is inextricably connected with the issue of the end of the Galactic CR spectrum and the transition to extragalactic CRs: in Ref. [6], the authors try to model the transition region by summing the Galactic SNR contribution and the flux of nuclei of extragalactic origin, required to fit the Auger **data** [4]. The authors reach the conclusion that in order to satisfy the observational requirement of a predominantly light composition in the EeV region [4,2,3,60], an extra component of extragalactic protons is required. Such an extra component appears to be in good agreement with the proton spectrum as measured by KASCADE-Grande [10]. However, both the proton and iron spectra measured by KASCADE-Grande in the energy region 10 16 −10 18 eV suggest that either the injection spectra are not cut off exponentially at the maximum energy (namely the number of particles decreases more slowly than an exponential at energies E ≫ EM ), or there is some, as yet unknown, class of sources with maximum energy much in excess of the knee energy.