An attempt was made to adapt the domain-wall size model to the explanation of magnetization mechanisms in real polycrystalline hard ferrites (SrFe12O19). Some new data concerning the total anisotropy specifically for polycrystals were discussed and its value deduced from natural spin resonance measurements. It was observed that samples with different Heff grain size and shape, can present different hysteresis loops. To explain these differences, we applied the theoretical expressions for the magnetization curve and the hysteresis loop developed earlier
