Intelligent Dynamic ANC 3.0FreeBuds 6i ANC 3.0 intelligent system works with cancellation of different types of sounds, with the ability to monitor environmental noise and adjust noise reduction performance seamlessly, 5kHz ultra-wide ANC frequency, improved noise reduction capability Perforated Base - Four 11mm dynamic magnet drivers are 50% more powerful and certified high quality, producing 14Hz perforated bass - performance that is sure to blow your breath. Fast Charging, Longer ListeningListen to incredible 35 hours with a fully charged case, or impressive 4 hours after just 10 minutes charging, to start and keep up without missing the pace. ANC Enabled, 20 hours of listening with a fully charged case, 5 hours of listening on a single charge. ANC off, 35 hours of listening with a fully charged case, 8 hours of listening on a single charge. Distraction-free Calling The headphones are equipped with three microphones that work in conjunction with a deep pneumatic network (DNN) algorithm to distinguish voices from sounds and cancel sounds during calls, so you can be heard loud and clearly. IP54 Sweat & Water Resistance - Explore the great outdoors or dive into intense workouts with peace of mind, with IP54 sweat and water resistance.