Sit Air is a portable pelvic support seat that is gentle on both the bottom and the lower back. Located almost at the center of the body, the pelvis connects the upper and lower body, protects internal organs and plays a vital role in supporting the body when walking, standing and sitting. Staying seated in the same position for a long period of time leads the pelvis to tilt backwards, putting pressure on the lower back and the sitting bone area which can dig into the chair and other surfaces, resulting in pain in the bottom. As the product developer has been suffering from back pain since his 30s that even affected his daily life, he developed the product based on his own experience and knowledge that supporting the pelvis upright when sitting improves posture and helps to relieve stress on the lower back. The main feature of this product is that it utilizes air pressure caused by the gravitational force on the bottom. In this way, the section behind and beside the bottom are inflated, and acts to prop up the pelvis. Because of the fluidity of the air, the bottom is gently encased even when tilted, and helps to relieve stress on not just the bottom, but also the lower back. The pelvis is built from various parts, and the product focuses on the tilt and structure of the largest bone, the ilium, through numerous trial and error to design the triangle-shaped parts. In addition, the inflatable product is easy to fold and carry around, providing comfort in any setting from airplanes to trains, cars, the office, living room, stadiums, theater and movies.