Experimental data are presented for an Fe-Al neutron polarizing supermirror on a Si crystal substrate with an antireflecting Cd layer. The polarizing efficiency of this supermirror is P ≥ 0.8 for the range of glancing angles θ{symbol}/λ = 0.25-1.7°/nm and P ≥ 0.95 for θ{symbol}/λ = 0.34-1.7°/nm. Some applications of this supermirror for thermal and cold neutrons are considered.