Available on all welded Steel, Aluminum, Stainless Steel, Standard Kits Steel, Aluminum Heavy Duty Kits, Steel, Aluminum, and Stainless Steel. A common and dependable Stairways Inc baluster. Available on all stair models/materials, working well with spiral stair railing interiors and exteriors. Aesthetically pleasing with any spiral staircase diameter less than 72”. Oak steps do not require collar, and good for contemporary appearances. Standard for all Heavy-Duty kits.