We love - and use - vintage kitchen items, they really are the best.
This vintage steel heat diffuser is an octagon shape, 9" across at the widest point. It is marked "AS France". I cannot find information about the company, but the diffuser dates from the 1930's - 1940's. It has a 6 1/2" handle, which folds for easy storage.
The heat diffuser has been used, and has been gently cleaned, but not scoured or polished. The vinyl coating on the handle is worn, as seen in the photos.
If you are not familiar with a stovetop heat diffuser, it is used to prevent hot spots in your pan. It is an important tool for making delicate sauces. They are often used in candy making, as well, to prevent scorching of chocolate.