By attaching the device to your body it shapes your posture straight and forms your back back to a straight posture over time.
The Device To Keep Posture Straight should fit your body without you feeling any pain. You should be able to adjust the Device To Keep Posture Straight to the degree that feels most comfortable for you.
The Device To Keep Posture Straight should be worn daily but depending on the instruction between 20-60 minutes for a couple of weeks to see some results.
Which means you should still move your body every day to strengthen your back.
Exercising or daily walks improve your back muscles and therefore your posture.