Fiberglass insulation has been the building-industry standard for most of the last half-century. Ring’s End carries fiberglass insulation in thicknesses from 3 1/2 in. to 12 in. with R-Values from R-13 to R-38. Fiberglass insulation comes either as rolls that have to be cut to length or as pre-cut batts that fit in standard stud bays, either 16-in. or 24-in on center.