For spin-polarized low-energy (0-50 eV) electrons incident on magnetized Fe(110) the authors have measured and dynamically calculated the elastic reflected current and the exchange-induced scattering asymmetry associated with it. The structure of the asymmetry is related to the spin-split band structure above the vacuum level. A large asymmetry peak around 5 eV, where the current is also large, is very stable against changes of the incidence angle and variations of the potential and the surface magnetization. This suggests a very efficient spin polarimeter.