Variation with height of the mean field strength ⟨ B ⟩ in several MHD models of the quiet solar photosphere. The black curves (solid and dashed-dotted) show the height variation of ⟨ B ⟩ that results from scaling factors F = 1 and F = 3 (see details in Shchukina & Trujillo Bueno 2011) of the magnetic strength in a MHD snapshot model resulting from the small-scale dynamo simulations by Vögler & Schüssler (2007). Red circles and crosses show the ⟨ B ⟩ values in the two snapshots we took from the small-scale dynamo simulations by Rempel (2014), with ⟨ | B_z | ⟩ = 80 G and ⟨ | B_z | ⟩ = 0.5 G. In both small-scale dynamo models, the net magnetic flux is zero. The thin blue solid curve corresponds to the time average of the ⟨ | B_z | ⟩ = 100 G model of Fabbian et al. (2012), which has a non-zero net flux and resulted from magneto-convection simulations without small-scale dynamo action. The top horizontal axis gives the mean optical depths log₁₀ ⟨ τ₅ ⟩ in the ⟨ | B_z | ⟩ = 80 G model of Rempel (2014), corresponding to the atmospheric heights given in the bottom horizontal axis.