There are two types of shielding typically used for cables: foil and braid. Foil shielding used a thin layer of aluminum, typically attached to a carrier such as polyester to add strength and ruggedness. It provides 100% coverage of the conductors it surrounds, which is good.ut braided shields do not provide 100% coverage. They allow small gaps in coverage. Depending on the tightness of the weave, braids typically provide between 70% and 95% coverage. When the cable is stationary, 70% is usually sufficient.