The SIHOO A3 office chair, an innovative ergonomic model, uses advanced technology to ensure comfortable sitting and proper posture. It features automatically adjustable 4D headrest, lumbar support, linked 3D armrests, an intelligent gravity mechanism, and automatic adjustment, along with a soft backrest and breathable mesh seat for all-day comfort. Its 3D headrest offers wide-angle adjustment (4.5cm up/down, 6.5cm forward/backward, 20° angle) and is made of soft mesh with a triangular soft elastic frame and support straps for back support; the 4-position adjustable 6cm liftable backrest suits all heights and auto-reverts to level 1 when at maximum height. It also comes with domino auto-adaptive lumbar support. The intelligent gravity mechanism with weight-adjustable resilience enables 2-step auto-adjustment and tilting from 92° to 100° to 112° (max), allowing comfortable rocking or short breaks. Certified by American BIFMA and German TUV, it has passed tests like backrest strength and seat impact tests, and is equipped with SGS Class 4 cylinders for durability and safety. It comes with a 3-year warranty, with support available for any product issues.