The hum by Colgate Smart Toothbrush Replacement Heads are designed by experts for a phenomenal clean. These sonic toothbrush replacement heads are designed to help you tackle hard-to-reach areas and features floss-tip bristles that take it easy on your gumline, rubber cups that polish, and a tongue cleaner that helps keep it fresh. Electric toothbrush replacement heads fit on all hum adult toothbrushes.