Thermoskin Lumbar Support provides pain relief and compression for muscle injuries and general lower back dysfunctions; injuries to the lumbar discs and the sacroiliac joint. This product has two flexible internal stays for additional support and adjustable elastic side straps for extra compression. Thermoskin Technology: Thermoskin provides effective treatment and pain relief for Sports Injuries, Arthritis, Repetitive Stress Injuries and many other conditions. Thermoskin combines compression, support and naturally generated body heat for therapy and pain relief. Trioxon Advantage: Thermoskin"s exclusive Trioxon lining is soft and comfortable against your skin. Trioxon captures your natural body heat for therapy and pain relief. The three dimensional Trioxon lining provides insulation and wicking of moisture via air circulation. This allows the skin to remain well oxygenated and comfortable for extended periods. Clinically Proven: Only Thermoskin is clinically proven to increase blood flow, increase skin temperature, increase muscle temperature and minimize perspiration. This provides heat therapy to prevent, treat and rehabilitate soft tissue injuries. Back/Lumbar Sizing Guide: Measure circumference around middle of the waist. X-Small 23 1/2 - 27 1/4 Inch. Small 27 1/2 - 31 3/4. Medium 32 - 35 1/2. Large 35 3/4 - 39 1/2. X-Large 39 3/4 - 44. XX-Large 44 1/4 - 48 1/2. 3X-large 48 3/4 - 53. 4X-large 53 1/4 - 57 3/4. 5X-Large 58 - 62 3/4 Inch.