Uniqueness Reduce Lower Back Strain 1 Decreases lower back muscles activities by 60%; 2 Increase productivity by 50%. Passive with No Power 1 No batteries, no acutators, no computers; 2 Waterproof, dust-proof and easy to maintain. Optimized Support 1 Minimal inhibition of arm, leg, and torso motions; 2 Support force optimized based on bending angle. One-size-fits-all 1 For a wide range of height and waist sizes; 2 Instant change of support force for different tasks, and fatigue level. Two Models 1 Model S: slightly lighter; 2 Model AC: compatible with LegX and ShoulderX.