Pipe Fitting Insulation Insulation Material Buna-N Rubber/PVC Installation Style Unslit Inside Diameter 4 1/8 in Wall Thickness 3/4 in Form Tee Minimum Operating Temperature -297 Degrees F Maximum Operating Temperature 220 Degrees F R Value 4.6 Color Black For Pipe Size 3 1/2 in Flame Spread Index 25 Foam Cell Type Closed Plenum Rating Plenum Rated Flexibility Flexible For Tube Outside Diameter 4 1/8 in Resistance Properties Antimicrobial Flame/Fire Retardant Standards UL 94