A typical skin deformation curve is illustrated in Figure 2 and the following parameters were analyzed: (R2) Ua (the ability of redeformation of skin)/Uf (final distension [skin distensibility]), gross-elasticity of the skin, including viscous deformation;16 (R5) Ur (immediate retraction)/Ue (immediate distension), net elasticity of the skin without viscous deformation;16 (R7) Ur/Uf, biological elasticity, ie the ratio of immediate retraction to final distension.16 The Reviscometer RVM 600 also allows for the evaluation of the mechanical properties of skin by measuring the propagation time of a shear wave between two sensors placed on the skin surface: one is transmitting an acoustical shockwave, and the other is the receiver.