Ceramic gas heater radiant brick insert flat grate style

Description

These are flat grate style radiants, measuring about 5 3/8" by 4" and 1 inch thick.  I have not been able to identify what model stove or heater they fit.  But, they might be useful for other purposes too, if you are creative.
There are 3 colors available, please see the photos for identification.
This item came from the liquidation of a hardware store, and is new old stock.  They may have markings from the store, or have a slightly dirty look...it was an old store.
Please ask if you need more information, and thanks for looking.
Most of my items are pre-owned, usually from estate sales, so I try to describe them accurately and show flaws in the pictures.  Any props in the picture, such as easels, ruler, or backdrops are not included.
Please contact me if you have any issues with your purchase and I will do my best to resolve it.
Thank you for looking!