• PLEASE DO NOT BUY IT UNTIL YOU TAKE AN ARMPIT TO ARMPIT MEASUREMENT. OTHERWISE, IT MIGHT NOT FIT YOU (read below). • DOWNLOADABLE INSTRUCTIONS AVAILABLE. ALSO POSTED AS AN IMAGE ABOVE (UPPER LEFT). • UNDERSTAND THAT IN SOME CASES YOU MIGHT NEED A HELPER TO PUT THIS ON Correcting bad posture is IMPORTANT! but you need external help, it is not as simple as just standing up straighter. Our Xforce correction brace is orthopedist-designed vest that gently aligned your shoulders into proper position to help prevent chronic neck and back pain and improve your posture. It adds more support and it also protects the body from further damage. Like any other body external device, it will feel a little uncomfortable the first time you wear it. However, The more you wear, the more comfortable it will feel. You will love our posture corrector once you get use to it. Be aware that in some cases it will not be easy to strap it yourself so you might need a helper. Size: Up to 30" (armpit to armpit). Read Below Armpit to Armpit Measurement. take the end of a measuring tape to the armpit area then go to other armpit, Use a helper since it has to be done on the back area. If it is longer than 30" this posture probably will not fit you properly. Please follow the above technique and make sure you are under 30" before buy it.. This support is one of our best selling item so we will continue working hard to improve its design. Please make sure this corrector carry the XFORCE seal. Otherwise, you are getting a different product.