Intertherm Roof Jacks Flue Assy 35" 63" Slant 4/12. Check manufacturer recommendations for other models to ensure compatibility. Roof Jack Vents are used to provide furnaces with fresh air for combustion and vent out flue gasses. This Flue Assembly features a 35" to 63" extension when measured specifically for the roof and a 4/12 slant (pitch). Features of Intertherm 903665A Roof Jacks Flue Assy 35" 63" Slant 4/12 Compatible with M1 Series Hot Surface Ignition Furnaces M1 Series Gas Gun Furnaces and M5 Series Oil Gun Furnaces from Intertherm Check manufacturer recommendations for other models to ensure compatibility Used to provide furnaces with fresh air for combustion and vent out flue gasses 35" to 63" extension when measured specifically for the roof 4/12 slant (pitch) Package Contents: Intertherm 903665A Roof Jacks Flue Assy 35" 63" Slant 4/12 Intertherm 903665A: Roof Jacks Flue Assy 35" 63" Slant 4/12