This adapter allows male valved paints such as larger high pressure Rusto, Rusto Universal, Krylon, Valspar, Killz Upshot, and other male valve spray paint cans with a 4mm valve size to work with male caps, such as Astro Fats, Pink Dots, NY Fats, German thins, Boston Thins/Fats and all other euro sized caps. Most caps fit on the adapter.