The socket is made with a generic 7 pin socket. The ground connections are finger stock soldered to copper. a 3/8" spacer is between the socket and the aluminum plate.

I found this material from a silicone hose supplier. The ID is 3.380". Perfect for an 8877 chimney. It's good to 500 degrees. I put 10kv on it with no leakage current. Go to