The Scandia SN-HG-4-SETEXT Set of Extensions is specifically designed for 40,000 BTU gas heaters, allowing for proper installation in walls with a thickness exceeding 5-1/2 inches. These extensions provide the necessary length to securely fit gas heaters through thicker walls, ensuring both safe installation and optimal heater performance. Ideal for sauna setups with thicker walls, this extension set makes installation flexible while maintaining the heater’s efficiency and safety.