Material subsurface scattering radius
Subsurface scattering radius is calculated in metric units and should rarely be over 0.05.
Always try to imagine how far should light travel under the surface of the material.
It usually won't be more than 1 - 5 cm - that's a value of max 0.05(for all 3 vector values).
Setting a realistic SSS radius also reduces noise in Cycles renders.