They come with a frame, a domed insert to wrap thin materials around or to paint/decorate directly, and a back to bring everything securely together.
This setting is platinum plated and 3 1/8” x a little over ½” or 55mm x 14mm in size.
They open up many possibilities not achievable with other settings!
This listing is for one frame only. Last picture shows a piece that I finished and is for presentation only.