The rail was custom made by a local steel fabricator in Marin but it is a fairly simple design of horizontal 3/4" steel rods welded to vertical plate for support. We set the verticals in a few feet on either side so that the corners are just the rods. The top rail is flat plate about 4" deep. The steel was then painted a blue grey to match windows.

Is it a costly railing??

Hmmm... good question. The material and fabrication were not that expensive but it was a bit tricky to install as they brought it out all in one piece then had to field weld to the uprights. Not sure how that would compare to prefab railing... probably a bit more expensive but worth it for the look.