Modern Timber Craft: Each and every heavy duty floating shelf bracket (Floating Mantel Bracket) is manufactured in the United States with 3/16" US Steel and can support up to 150 lbs plus the weight of the shelf. These pair perfectly with our 3x5, 3x7, 3x8, and 4x8 reclaimed mantel shelves that are anywhere from 24 to 42 inches in length.