The Dielectric Shielding node adds dielectric shielding as a boundary condition. It describes a thin layer with thickness ds and a bulk relative permittivity; εr that shields the electric field:

The Material type setting decides how materials behave and how material properties are interpreted when the mesh is deformed. Select Solid for materials whose properties change as functions of material strain, material orientation and other variables evaluated in a material reference configuration (material frame). Select Non-solid for materials whose properties are defined only as functions of the current local state at each point in the spatial frame, and for which no unique material reference configuration can be defined. Select From material to pick up the corresponding setting from the domain material on each domain.

The default is to take the Relative permittivity εr (dimensionless) values From material.  It takes it from the adjacent domains if not explicitly defined. For User defined select Isotropic, Diagonal, Symmetric, or Anisotropic and enter values or expressions in the field or matrix. Enter a Surface thickness ds (SI unit: m) of the shielding. The default is 1 m.