6 Pack of Ceramic Egg Isolator. High Power. MFJ Ceramic Egg Insulators are the same tried and true antenna building accessories that have been used since the earliest days of radio. These authentic glazed-ceramic egg insulators feature 7/16-in. holes that allow the use of heavier rope or messenger cables, but also facilitate many types of antenna wire. These classic antenna insulators are 2-1/8 in. long. They are made of heavy-duty ceramic material and can handle all the power you throw at them. They can handle heat and will not melt like the plastic insulators do. These insulators are TOUGH!