Clearance: 6" for Double-wall DVL. This product MAY NOT be used after the first transition piece (wall-thimble, or ceiling support), the pipe is designed for interior use. Temp Ratings: 1000-F Continuous Burn (UL 103)2100-F Intermittent Burn (UL 103). Material (DVL): 0.016" Stainless Steel. Insulation (DVL): 1/2", Air. Joint/Connection Overlap: 1-1/2". Joint/Connection Type: Twist-Lock. Supported Fuels: Wood. Finish: Black. Material: 26 Gauge Aluminized Steel.