R19 23 x 39 2 Kraft Roll Fiberglass Insulation Batt Thickness 6-1/2 75.07 SQFT Per Bag. Johns Manville Formaldehyde-free Kraft-faced rolls are for use in 2 x 6 exterior sidewalls basement walls garage walls floors and ceilings/attics. Kraft facing serves as a vapor barrier to help manage moisture and includes tabs for easy stapling to wood framing. This product helps save energy and provides good sound absorption. The glass fiber will not settle rot mildew or deteriorate. Rolls can be cut to any length. This product has been GREENGUARD certified for superior indoor air quality.