it ensures a flush fit and proper latching

When troubleshooting Lennox error code 201

Precision Thermal Trip: Factory-rated at 208F (98C) to ensure accurate circuit interruption before equipment failure

It is also found in specific PAE

this limit switch serves as a primary safeguard by monitoring for restricted airflow or draft obstructions within the venting system

Rheem-Ruud SP10399B Pilot Assembly it ensures a flush fitEnsure reliable ignition and peak burner performance with the Rheem Ruud SP10399B Natural Gas Pilot Assembly. Designed as a genuine PROTECH OEM replacement part, this assembly is engineered specifically for compatibility with Rheem and Ruud commercial and residential gas water heaters, including the R & RCD Series. Utilizing natural gas (NG), the SP10399B provides a stable, consistent pilot flame necessary for the proper cycling of the main burner