1. There are 3 sizes for the lumbar support strap: L (length: 100 cm 39 inches, fits waist: 80–100 cm 31.2–39 inches), XL (length: 115 cm 44.8 inches, fits waist: 100–117 cm 39–45.6 inches), XXL (length: 125 cm 49.2 inches, fits waist: 117–140 cm 45.6–54.6 inches). Please measure your waist and choose the right size accordingly. 2. The back support features 2 Velcro fasteners for double adjustment, providing strong compression and support for the waist and abdomen. The inner elastic belt functions like a corset to correct posture and support the lower back, while the outer elastic Velcro closure reinforces compression as needed. 3. With 8 springs sewn into the lumbar spine, the back support belt effectively supports your lower back while allowing full range of motion for daily activities. 4. The back strap helps prevent injuries during sports. Ideal for sciatica, herniated discs, scoliosis, spinal stenosis, hip pain, postoperative rehabilitation, and more.