In addition, it doesn't wear out over time like a traditional rubber gasket found in other spark plug sockets. Work on a variety of engines and need a set of spark plug sockets of varying sizes?

This can cause the socket to short circuit and blow out the fuse, but it can also prevent accessory plugs from making contact ...

The rubber gasket or magnet will help prevent the spark plug from falling out of the socket as you remove it from the tube, as well as help you to install new plugs after removing the old ones.