This is a two cup measuring cup from McKee. I've found that McKee glass is more opaque and a warmer green, rather than cooler like Fire-King. The McKee mark is on the bottom - see photo 5. It has a thick sturdy handle and is 3½" tall. Its measures up to 2 cups and the marks are different on both sides marking 2 cups, 1 pint and 16 oz. It is in very good condition with some light grey circular marks inside the bottom. The last photo is a whole group of McKee pieces.
"McKee was the first company to mass-produce jadeite dinnerware in the '30s. You can identify McKee jadeite by the letters "McK" in a small circle on the back. Fire-King shakers are indeed all shaped the same, but none of them are square. Comparable pieces are either Jeannette or McKee. At first glance they may appear to be identical, but the McKee shakers are slightly taller and have wider necks. Incidentally, McKee and Jeannette shakers are from the 1930’s. They come in a variety of colors and lettering styles. All are highly collectible."
All information I have read indicates that these pieces should not be put in a dishwasher because they will lose their shine. I'm happy to ship outside the United States; please convo for a mailing cost.