Mixing cup for Model 51 mixer. The Model 51 mixer was made between 1951 and 1963. Because the original cups were plastic, not many survived over the last 50 years.
The cup holds a little more than a pint. Double bottom with ring so it doesn't slip off the bottom holder.
Stainless steel. Imported.
It's a good idea to check the feet on your mixer, as they become brittle and should be replaced. Otherwise, when in use deteriorated feet can cause damage to and slippage on the counter top.