I've had this for decades, I think my aunt sent it to me not long after I married in the early 1960s. It is unmarked but is identical to the Glasbake teapots (made by Pyrex) that have been shown in several books. Recently, my cousin Mason phoned and I mentioned it to him and he remembered that she had purchased it during a trip to New York City in January 1938, because it was unusual, the only one in the display and a "new product". (She was also a collector of teapots.) Maso...n said that he thought it was a prototype for the ones that were introduced later in the year. There is what appears to be a mold mark Photo #2 and another mold mark but doesn't go all the way to the bottom. #3. I have had other Glasbake pieces like this, made in 1939, and the hardware is identical but painted red, and the handle is the same but on this one is slightly askew. In any event, it is an interesting piece in my collection that I am now selling as I am trying to reduce the number of Items I have.