1. Size: Find the circumference of your waist at its narrowest point in inches with a soft/flexible tape measure. Size: S fits waist in the range of 23.6 31.5 inches, M fits waist in the range of 32.8 35.4 inches, L fits waist between 36.7 40.6 inches, XL fits waist from 42 46 inches. 2. BODY SHAPING: This back support can be used to shape your body according to your own conditions, making you look slimmer. With prolonged use, it may even help reduce belly fat. It is thin and remains invisible under clothing. 3. FULL BODY SUPPORT: Our posture corrector features a humanized design. It supports your back and keeps the spine straight, protecting you from movements that could hinder recovery from mid or lower back injuries. 4. EASY TO USE: Soft padding, breathable materials, and a spine cutout ensure comfortable wear. Fasteners and quickrelease mechanisms make it easy to put on, take off, or adjust. No special tools are required for adjustments.