For use when you need to separate the insulation material from the inspector. Whether it's keeping the inspector safe from insulation material such as asbestos or if you just want to prevent accidental wall damage to the insulation, the extension sleeve is the simplest answer to your problem. APF has the only inspection port on the market that was designed specifically to accommodate an extension sleeve when needed. During the installation process, the extension sleeve is slipped over the center draw of our flange and inserted into the inspection chamber. The silicone that is applied under the flange during installation bonds the extension sleeve to the flange for a permanent solution to your material separation needs.