 Now, it's $75 a chimney to get it sealed. So what they're talking about is a masonry sealer, and you probably don't need this. It's not like you need it to protect it. Usually, you put sealers on if you're concerned about leaks. But if you are going to put a sealer on it, they're silicone-based, and you have to make sure that you use one that's vapor permeable. Some of the older sealer products out there are not vapor permeable, and that means that moisture gets in, it gets trapped under the surface of the concrete, and then it'll freeze and spall or crack.