The twig of Salvadora Persica tree that has been practised by humans since thousands of years ago before the invention of plastic toothbrush and chemical filed toothpaste. Simply peel about 1cm of the bark to reveal the insides. Chew on it until they fray slightly and resenble bristles. Brush all parts of your teeth, whenever, wherever. No water is needed. People use it while watching tv, reading emails, reading. Peel a new layer once it overfrays. 1 stick can last for a month if used daily.