Suitable for Flat or Round Handrail Finish ASTM A480 No 4 linearly textured satin finish Stainless Steel AISI 316 Marine Grade for outdoor and indoor areas Suitable for round handrail up to 1 3/4" diameter Mountable into wood stud, steel stud, or concrete The Stainless Steel Wall Bracket Square for Flat Bottom Tube is modern in design, easy to install and safe and sturdy upon completion. This bracket leaves a 1 9/16" gap between a wall and the top rail, meeting ADA requirement of a 1 1/2" gap. Also, our detailed instructions below ensures a smooth installation and results in a dependable handrail.