It's one of these kits, and yes they call it ribbon sealer. A paint store such as Mattos or McHenry Auto Paints would have it cheaper than the local Autozone or Pepboys.
They make three different thicknesses. Replacement glass is sometimes a different thickness than original and the chrome won't look good with the wrong ribbon sealer. The last owner of my car used ribbon that was too thin. That put the chrome flush with the body and it looked kind of flat compared with how it's meant to be.
