This is the gasket strip that is glued to the inside of the gasket cover. Remember to get the glue adhesive if you are planning on repalacing this part.

It creates a tight, airtight seal between the removable end cap (the cover that gives access to the motor and internals) and the main dryer body. This prevents pressurized air from leaking out around the edges instead of going through the hose. Good sealing = stronger airflow, quieter operation, and better overall performance.