Abstract: A blank for a spacer for an insulating window unit preferably includes a core made of a metal sheet, e.g., stainless steel, and a coating made of a synthetic material, e.g., polypropylene. The coating preferably has a thickness in the range of 0.02 to 0.2 mm and the core preferably has a thickness in the range of 0.05 to 2 mm, more preferably between 0.1 to 0.3 mm. Further, the insulating window unit preferably includes at least two glass windows, which extend in parallel and are spaced a first distance from each other. The first distance preferably is maintained by the above-mentioned spacer, which spacer is adhered to the glass windows using an adhesive or a sealing compound.