Winsor & Newton are committed to making The World’s Finest Artists’ Materials, so its no surprise that their Kneaded Putty Rubbers are an essential tool for any artist. These are "plastic" or "putty" erasers, which you can mould to a fine point & use to erase the tiniest details & to pick out highlights. Theyre equally effective on pencil, chalk & charcoal, erasing effectively without smearing. We sell two sizes of Winsor & Newton Kneaded Putty Rubbers: large & medium.