I swooned when I saw this, among the most beautiful readymades I've ever seen! As far as antique ventilator grates go (ha!) this is a rare and highly collectible one, and this one has held onto its color beautifully, including some old red paint still on the center knob, which operates smoothly to open and close the grate. With an 1877 patent date on one side and just truly gorgeous; I'd hang it on the wall straight away.
7 inches in diameter. Excellent, perfectly aged antique condition.