Indicator Deep Clean yellow bristles are designed to slide between teeth to clean hard-to-reach areas. Ergonomically designed handle for comfort and control. Blue Indicator bristles lade halfway so you know when to replace your brush. Dentists recommend changing your brush every 3 months. Clinical research proves that a new toothbrush can remove up to 30% more plaque than one 3 months old (Research with a flat trim toothbrush). Made in USA.