In the 1940s and 1950s several bicycle producers made bikes with elegant head tubes which were designed for these semi-integrated headsets. Two pieces of the headset are pressed as inlays into the frame itself and serve as inner races. The other, chromed parts, serve as outer races.
Honestly cool stuff.
Outer diameter of inlays: 1 1/2" or 38mm
Actual race diameter: 1 1/4"