Material: ABS + woven elastic belt, Built-in 400mah battery, intelligent induction, vibration reminder, free adjustment, light and breathable, vibration reminder when bent 25 Instructions: Put it on (correct wearing direction: the button is at the top, the light is at the bottom) get your posture where you want it, and hold the button for 2 seconds to turn it on. Innovative Concept : When the smart sensor performs angle monitoring, it automatically triggers gentle vibrations hunchback sensed, reminding you to adjust to the correct posture, finally to form good posture habits, protect eye vision and relieve back fatigues. (Attentions;People with serious back problem should seek helps from a doctor or hospital) Health Correction: We recommend that users wear the posture corrector for 2 hours per day. 21 days is the period of habit formation, change bad habits develop an upright posture, 90 days posture will be significantly improved. As you are trained to stand straighter, you'll need to use it less and less. Adjustable Shoulder Strap: Suit for kids and adults, you can use it with your family in different time. If the posture reminder is not sensitive or too sensitive, please get your posture where you want it, then reboot.