Can this be used for stair handrail or is that a separate product?

The Gilpin Patterson railing can be racked (or bent) for stair use. Simply hold the bottom channel firmly in place with your feet and push the top channel towards one end. This will allow the railing to shift for stair application. The top and bottom channels will need to be trimmed to butt against the posts and the cuts must be painted with rust inhibiting paint like Rustoleum or Krylon.