Say goodbye to guesswork! With iO refill technology, your brush head knows when it's time for a change. Watch the magic unfold as the color transforms from vibrant blue to pristine white, signaling when to it's time to change and ensuring a fresh and effective clean every time. The iO collection is Oral-B’s best technology. These replacement brush heads contain High Density Dentist-inspired extra soft bristles for a gentle clean. Optimized bristle patterns adapt to the curves of the teeth and gums but are extra soft for maximum comfort. Precision fit with a gentle clean. Compatible with Oral-B iO Electric Toothbrush Handles. Dentists recommend changing your brush head every 3 months for best results. You will receive 4 Oral-B iO Gentle Care Replacement Brush Heads. Best of all, it is brought to you by Oral-B—the #1 brand used by dentists worldwide.* *Based on surveys of a representative worldwide sample of dentists carried out for P&G regularly. Do not use on children under age 3. Replace brush every 3 months or sooner if brush head becomes worn.