Not Pyrex, I know; they are marked Hazel Atlas, and I have a soft spot for HA because my grandmother worked there for years, so I always think there's a chance she might have made anything I find. I had no idea what they were until I found them on etsy. Who would have thought furniture casters would be made of glass! I'm planning to use them as tealight holders! $2 for the entire box of 20 (5 large and 15 small) so even tho I had no idea what they were, it was totally worth it for the mystery.