I assume from the title of your post that you are referring to cold light sources. Contact the Aristo Grid company in New York. They have a site but I have lost the bookmark. Calumet Photographic and others handle the products. They make a unit that will fit just about any enlarger made. Almost all knowledgable black and white printers use this light source instead of condensers in their enlargers.(posted 9236 days ago)Hope this helps, and hope someone can come up with the URL for Aristo Grid.