· [Ultra Lightweight and Compatible for Small Ear] The surface and Angle of A1 earbuds in-ear part have been polished and refined repeatedly to achieve a balance between beauty and comfort and make it comfortable to wear. Likewise, a single earbud weighs only 3.7g, making it as light as a feather and discreet in the ear. Ergonomic design provides a comfortable and secure fit that doesn’t protrude from your ears especially for sports, workout, gym.· [Optical Sensors Technology] Features optical sensors technology, they sense when they’re in your ears and pause when you take them out. Adopt high-precision contact sensor, optimized for daily use and sports occasion, achieving real-time detection of wearing status.· [Transparency 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.· [Bass Enhancement] TOZO A1 earbuds’6mm diameter speaker presents a powerful and wide sound range, which makes the treble full of dynamics, and the bass powerful.· [Charge on the Go] TOZO NC2 wireless earbuds can last for over 10 hours' playtime from a single charge and total 42 hours with the compact charging case. Providing convenient charging way with no strings attached. IPX6 waterproof can prevent from the damage of the splash by sweat and raindrops.