Staircase width of 24in to 60in: 2 risers recommended. Staircase width of 61in and more: 1 stringer required at 36in max.The easiest way to build a solid and lasting staircase. Light and easy to handle, this stringer is quickly installed. One-piece design, ready for step installation. No more complicated assemblies! This aluminum stringer is maintenance-free. It will highlight your staircase and add a finishing touch to your house. Can be used with steel, wooden, fiberglass, etc. steps and guard rails. Baked powder coating finish.For a patio height of 11½ in to 18½ in.