41,000 Vibrations per Minute Sonic Motor with 4 Modes An incredibly powerful 41,000 VPM sonic motor delivers a complete and thorough clean. Use Whiten mode towards the end of brushing sessions to dissolve surface stains. Use Massage mode to deliver vibrating micro-bursts into gum tissue to improve circulation and tissue function. True Wireless Charging A single overnight charge will last a full 30 days. The included travel case lets you take your black series on vacations both short and long without needing to take your charger. Smart Vibration Timers A built-in smart chip coaches you to a healthier smile by offering a 30 second vibrational "nudge" so you know to move on to a new quadrant of your mouth. An auto-timer powers black series down automatically letting you know you've brushed for the full dentist recommended 2 minutes.