【Active Noise Cancellation】Hybrid 3 layer Active Noise Cancellation. 1. Outward-facing microphone detects external sounds and counter with equal anti-noise to first cancel noise. 2. Inward-facing microphone listens inside ear canal to pick up internal sounds and produce anti-noise again to twice cancel the left noise. 3. Ear caps prevent 90% noise going to ear canal. 【Transparent Mode】 You can hear what you want to hear, which lets outside sound in so you can hear and interact with the world around you. You can clearly hear the announcement of the airline or subway and what is saying around you without taking off the headphones. 【Built-in Dual Noise Cancelling Microphone】Double microphone noise reduction system suppresses environmental noise. A dedicated internal and two external microphones pick up your voice and isolate it from outside noise. 【One-step Pairing】Pick up the two headsets from the charging case, and they will be paired automatically. Then simply enable bluetooth connection on your mobile phone to pair the device with your earbuds. 【Charge on the go】TOZO NC9 wireless earbuds can last for over 10.5 hours' playtime from a single charge and 24 extra hours in the compact charging case. In the Active Noise Cancellation mode can last for over 7 hours' play time.Providing convenient charging way with no strings attached.