This is a Revere double boiler insert designed for use with the 1930s through 1970s vintage Revere Ware copper-clad saucepans. It's the smallest size they made (and probably the hardest to find), to fit a 1-quart to 1-1/2 quart saucepan, or any pan that is 5-5/8" to 5-7/8" diameter and at least 3" or more deep. The stainless steel insert measures 7-3/4" handle to handle (just over 6" without the handles) and is 2-3/8" deep. The stainless steel finish is in excellent condition, clean and shiny with no dents or dings.
Revere Ware 1 Quart Double Boiler Insert