The mechanical properties of honeycombs depend on its cell geometry, the properties of the material from which the honeycomb is constructed (often referred to as the solid), which include the Young's modulus, yield stress, and fracture stress of the material, and the relative density of the honeycomb (the density of the honeycomb normalized by that of the solid, ρ*/ρs).[29][30] The elastic moduli of low-density honeycombs have been found to be independent of the solid.[31] The mechanical properties of honeycombs will also vary based on the direction in which the load is applied.