Abstract: A cylindrical radially shrinkable sleeve (10) for enclosing a connection or an end termination of an electrical cable having an insulation surrounded by a shielding layer. The sleeve (10) has an outer shielding layer (16) of semi-conductive material and at least an insulation layer (14) on the inner side of the shielding layer (16). The cylindrical layers are made of flexible material adapted to be retained in a radially expanded state by a mechanical support. The radially innermost layer is of a homogeneous material having a relative dielectric constant which is larger than that of the insulation of the cable. The material is a matrix of dielectric plastic material containing microspheres which are electrically conductive either totally or only at the outer surface thereof, and which have a diameter between 10 and 500 .mu.m. The microspheres are uniformly mixed into the matrix material, with the compound having a dielectric constant equal to or larger that 3 in a dielectric strength of at least 5 kV/mm.