Here is the real deal. This is an adjustable floor register that fits around a standard 6 stove pipe. The piece says that it is patented and made of "ferrosteel, " but has no maker's mark. It has a little cast-in knob that allows you to adjust the air flow with your foot. No need to bend over.It also has the center insert that allows you to move the stove, either seasonally or permanently, without leaving a hole in your floor. They work great and used to be common.
Most building codes now require that a through-floor heat duct be metal lined, so you may have to do a little sheet metal work to get this to meet code. Or, you can simply put it on display. The item "Vintage Ornate Cast Iron Stove Pipe Floor Register Grate" is in sale since Thursday, October 15, 2015. This item is in the category "Antiques\Architectural & Garden\Hardware\Heating Grates & Vents". The seller is "gnome-honey" and is located in Seattle, Washington.
This item can be shipped to United States.