Clear Stair Inside Corner Dust Guards Decorative Triangle - Temu
Brass Staircase Dust Corners | Van Dyke's Restorers
Stair dust corners introduced at the end of the 19th century to make sweeping easier. They keep dust from accumulating in the corners : r/Damnthatsinteresting
Dust Corners Polished Brass, Each side is 2 3/4" in length