Superior 24-Inch Rigid Stove Pipe for 4.5x7.5-Inch SecureVent Direct Vent SystemThe Superior 24 Inch Rigid Stove Pipe for 4. 5x7. 5 Inch SecureVent Direct Vent System provides a premium accessory for use with your gas fireplace. Featuring heavy duty aluminized inner and galvanized steel outer construction, this unit has been built to last. A 4. 5 inch inner diameter and a 7. 5 inch outer diameter create an ideal size for many applications. This rigid direct vent venting allows for safe and efficient ventilation of a compatible