Note that The quantities ε ε SI / ε ε 0 , ε ε HL and ε ε G are dimensionless, and they have the same numeric value. By contrast, the electric susceptibility χ χ e is dimensionless in all the systems, but has different numeric values for the same material: χ χ e SI = χ χ e HL = 4 π π χ χ e G The same statements apply for the corresponding magnetic quantities.