Use as many of these as needed when the wall, for any reason, is too thick causing the mounting plate in the wall and wall plate to not meet. Longer screws will be needed as well. Each extension adds 3/4 of an inch and can be cut to shorter sizes.
Fits SilentMaster, MD, ModernDay, FloMaster, and others. Only one of these filters is needed in all these units. One mesh replaces three (mesh, foam, mesh) that were installed previously in some units. Can be cut to shape for some such as Vacumaid.