The outer ring mounts to the floor. It is 15.5 inches in diameter. The inner ring spins to adjust the heat and the center circle is removable for servicing the vent. Center plate is 6 inches in diameter. It is heavy and strong.This item is in the category "Antiques\Architectural & Garden\Hardware\Heating Grates & Vents". The seller is "collectitforyou" and is located in this country: US. This item can be shipped to United States.