https://www.amazon.com/Universal-Ele...ords=coax+seal
You can also try Coax Seal linked above. I believe you can also find it at some electronics stores and if memory serves me, I think the company that manufactures it has a website.
I have found it easy to use and remove, but I've seen a comment or two in the past on the Net from those who didn't seem to like it. But I would recommend it.
All the best!