This category includes additional materials that help eliminate noise, rattles, and vibrations that standard layers can’t fully address.

These materials are used to stop squeaks, seal gaps, protect edges, and isolate plastic or metal parts from touching each other. They’re especially helpful for interior trims, dashboards, door cards, wiring, and small problem areas where noise often comes from.

While they’re not always visible, these materials play a big role in achieving a quiet, solid, and rattle-free cabin, especially in older cars or vehicles with lots of plastic panels.