What is a characteristic feature of SF6 bushings?

SF6 bushings are characterized by being filled with sulfur hexafluoride (SF6) gas. This gas is known for its excellent insulating properties and high dielectric strength, which make it very effective in preventing electrical discharges. SF6 is particularly advantageous in high-voltage applications because it can withstand much higher voltages than air or other gases.

The use of SF6 gas allows bushings to maintain a compact design while providing effective insulation. This feature is significant when considering the safety and efficiency of electrical systems, especially in substations and switchyards. The other options relate to different materials or properties that do not accurately describe SF6 bushings, which specifically rely on this gas to enhance their performance in electrical engineering applications.