These Oral-B CrossAction Replacement Electric Toothbrush Heads (4-pack) are compatible with most Oral-B electric toothbrush handles including the Pro 1000, Pro 500, Vitality, and more. The CrossAction design features bristles angled at 16 degrees to surround and clean each tooth individually for a superior clean versus a regular manual toothbrush. Blue indicator bristles fade halfway to signal when it's time to replace the head every 3 months. Clinically proven to remove up to 100% more plaque along the gumline than a regular manual toothbrush. Comes in a 4-pack for several months of use. Fits all Oral-B electric toothbrush handles with the round head connector (not compatible with iO series).