Johns Manville Formaldehyde-free fiberglass batts are ideal for insulating and sound proofing 2' x 4' stud wall cavities with 16" on center spacing (exterior sidewalls, basement walls, floors and garage walls). Kraft-facing serves as a vapor barrier to help manage moisture and includes tabs for easy stapling to wood framing. Glass fiber will not settle, rot, mildew or deteriorate. Convenient pre-cut batts mean less cutting. This product has been GREENGUARD® certified for superior indoor air quality.