Similarly, PE and the sister compound XLPE are commonly used because of their very good electrical properties. Some examples of this are foamed PE, which garners better electrical properties and cost savings, and XLPE, which has enhanced chemical and thermal properties. PE is most commonly used as the insulation in Ethernet cables while XLPE is commonly used in hook-up wire and as insulation in instrumentation and tray cables. XLPE is generally not used as an outer jacket material.