Feature: 1. This smart posture corrector has voice and vibration dual reminders, which can help children improve their bad posture. 2. It can correct posture scientifically, cultivate physical memory, and help shape a good figure. 3. You only need to wear it for two hours a day, and you can see the effect if you stick to it. 4. The central switch on the back of this posture corrector can be easily turned on by adults and children. 5. Small and light, easy to carry, the shoulder strap can be adjusted freely, comfortable and breathable. Specification: Item Type: Smart Posture Corrector Material: ABS, Nylon Battery Type: Lithium Battery Battery Model: Lithium Battery 5V 200mAh (Delivered with Built in Battery) Charging Power: 5V-2A(Maximum) Charging Time: 40min Charging Output Interface: USB Universal Interface Host Size: Approx. 9x9cm / 3.5x3.5in . Package List: 1 x Posture Corrector1 x USB Charging Cable Note: Use reminder:1. Adaptation period: Don't be too tight, let the back adapt first.2. Adjustment period: slightly increase motivation according to your endurance and body type.3. Maintenance period: stick to wearing and develop good habits.