The 4-shelf book case has all steel construction. All shelves adjust in 1" increments 13"D shelves easily accommodate 3-ring binders. Shelf count includes bottom of bookcase. Units assemble easily heights align with CSII Desking Hutches. Backed by Mayline"s Limited Lifetime Warranty.All steel construction. Shelves adjust in 1" incrementsShelf count includes bottom of bookcaseFinish Black Paint