Pipe Fitting Insulation Insulation Material Cellular Glass Installation Style Slit in Half Inside Diameter 1 3/8 in Wall Thickness 1 in Form 90 Degrees Elbow Minimum Operating Temperature -450 Degrees F Maximum Operating Temperature 900 Degrees F R Value 3.5 Color Black For Pipe Size 1 in Flame Spread Index 25 Foam Cell Type Closed Plenum Rating Plenum Rated Flexibility Rigid For Tube Outside Diameter 1 3/8 in