ultrasonic vibration can effectively remove the dental tartar, calculus, plaque, tea, and smoke stains, whisper-quiet without disturbing others, mild and painless to avoid damaging your teeth. five adjustable gear levels allow for the quick switch by one-button control, suits to different teeth types, and meet multiple applications. built-in high brightness led auxiliary light helps to avoid dead ends with a clearer viewing effect, making teeth cleaning a breeze. eco-friendly and lightweight material for carrying convenience, interchangeable heads for easy cleaning, hygiene, and maintenance- suitable for both home and travel use. you can't feel the vibration while touching it by hand even if powered on, it will start to work and get a sound once touching the teeth..syi