This is a Revere double boiler insert designed for use with the 1930s through 1970s vintage Revere Ware copper-clad saucepans. It will fit a 3, 3-1/2, or 4-quart deep saucepan, or any pan that is 7" to 7-3/8" diameter and at least 4-1/2" to 5" or more deep. The stainless steel insert measures about 9-1/2" handle to handle (just over 7-1/2" without the handles) and is 4" deep. The insert is shown in the last two photos with a 3-1/2 quart saucepan (not included).
The stainless steel finish is in clean, shiny condition though there quite a few tiny stir marks in the bottom from use and cleaning. The dark spots in the photos are from glare and shadows.