On a brass rail, the hardware is part of the finish, and visible screw heads on a flange can spoil it. The 510U/1H solves that with a plain base: drill it to the pattern the wall needs, hide the fasteners where they work best, or bond the flange with a structural adhesive and leave the face untouched. The collar takes 1.5-inch OD tubing and locks it with a set screw, the same as the standard 510/1H. It is cast in solid polished brass, not plated, so it can be polished back to full shine after years of handling or left to develop a natural patina. Use it with the 1.5-inch brass tubing, brass end caps and finials, and the brass saddles and brackets in the same family for a period rail that matches from end to end. Ships from US inventory.