Charging function We provide a USB charger to save you the trouble of buying batteries. The device can be easily turned on/off using the power switch. The volume can be easily adjusted by just touching the button without any tools. And he can be charged anywhere there is a USB socket, such as company computers, home sockets, etc.Four models 4 adjustable volume modes to ensure clear sound can be heard in any environment. Simple one-handed operation, fast and convenient, suitable for all kinds of people, including the elderly.Charging BoxMachines can be fully charged within 2-3h and can reach an ultra-long standby time of 35-48h after being fully charged. With the current smaller appearance as well as the small charging case, meet your convenience to carry as well as invisible wear, use anywhere, anytime.Customised designWeighing only 3 grams individually, it is easy to wear. Easy and comfortable to wear. Comes with different sized earplugs to perfectly fit each individual ear.