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. 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.