Up to 50-hr Playtime--Jam to Music All Day and Night Necklace 4 provides an ultra long music-listening experience. Up to 50-hour playtime allows you to charge your Necklace 4 once a week. Charge 10 Mins, Play 10 Hours--Charge as A Flash Just 10-min fast charging can provide 10-hr music listening, making you music play on and on. Noise Cancellation in Calls--Designed for Clear Calls Necklace 4 is featured with proprietary noise-cancelling algorithm and inline microphone, which helps reducing surrounding noise and providing clear voice in calls. Magnetic Lock--Intelligent Switch Each earbuds has a built-in magnet, allowing you to get away from tangle-free carrying, get easy storage, and make a intelligent switch. Power on: Split the magnetic earbuds Power off: Clip the magnetic earbuds on Dual EQ--Switch As You Like Short press the Mode button "M" once to switch between Normal Mode and HavyBassTM Mode. IPX5 Waterproof & Sweat Protection--Not Afraid of Water and Sweat