The thumb slide at the top easily moves the vent plates. The top diameter is 10 1/2", the bottom diameter is 8 5/8", and tapers slightly toward the top. The inside of the vent plates are marked 9.
The item "Antique cast iron heat vent round floor grate ornate design" is in sale since Friday, December 08, 2017. This item is in the category "Antiques\Architectural & Garden\Hardware\Heating Grates & Vents". The seller is "sandinmyshoe" and is located in Tafton, Pennsylvania. This item can be shipped to United States.