I bought these brushes for cleaning various things (such as the type blocks of my 1929 Underwood No. 5 typewriter [I only used the nylon one!]). They are good for various cleaning tasks and for various materials. I would say that the metal ones should only be used on unpainted hard metals to avoid scratching the surface, while the nylon one is pretty safe for many surfaces. The brushes arrived on time and well packaged. I was satisfied with my purchase.