Johns Manville Formaldehyde-Free™ Fiberglass Insulation (Specific for 2" by 4" STEEL framed walls with joists spaced 24" apart) R-Value: 12 Dimensions: 3½" x 24" Coverage: 160.00 sq. ft./bag (NEW bag size) Application: Interior Walls JM Formaldehyde-Free™ fiberglass insulation promotes better indoor air quality, provides superior thermal efficiency and a reduction in sound. Data Sheet