Oral-B iO Electric Toothbrush Heads Refill Gentle Clean Ultimate Clean Replacement Tooth Brush Heads for Oral B IO7 IO8 IO9The Ultimate Clean replenish combines new bristlewith 3700 filaments. Tuft-in-Tuft bristles for interdental cleaning in hard-to-reach areas. Bristles are accurately angled at sixteen phases to maximum efficiently but gently sweep away plaque alongside the gum line. The Oral-B iO Gentle Care Refill Brush Head has 4000 filaments for a mild to protect touchy tooth and gums and high-quality cleaning experience Round brush head bristles surround every single tooth