R11 3-1/2 x 15 X 40' KF INSUL 50 SQ.FT. ROLL, was # 910057 | R-11 Fiberglass Kraft Face Roll
3-1/2" x 15" x 40'
50-Sq. Ft. per bundle
"R'' stands for resistance to heat flow. The higher the R-value the greater the insulating power.