Pipe Insulation Insulation Material Cellular Glass Installation Style Slit in Half Inside Diameter 2 1/8 in Wall Thickness 1 1/2 in Overall Length 2 ft Minimum Operating Temperature -450 Degrees F Maximum Operating Temperature 900 Degrees F Facing Material Unfaced Color Black R Value 5.17 Form Tube For Copper Tube Size 2 1/8 in Flame Spread Index 25 Foam Cell Type Closed Plenum Rating Plenum Rated Flexibility Rigid For Tube Outside Diameter 2 1/8 in