The ThunderX3 CORE SMART is a mesh ergonomic chair with automatic lumbar support built into the backrest -- it flexes to follow the spine's natural curve as you shift position, rather than relying on a fixed lumbar pad. It uses a synchronised tilt mechanism with a recline range of 90-125 degrees, 3D-adjustable armrests, and a Class-4 BIFMA-approved gas lift. Overall dimensions are 70cm x 70cm x 139cm, with an 86cm backrest, 50cm seat depth, 53cm seat width, and seat height adjustable between 46-56cm on 75mm casters. Rated up to 150kg maximum user weight (some regional listings specify 125kg -- check the product label on arrival) and recommended for users 155-190cm tall. A good fit for long work-from-home or gaming sessions where automatic lumbar support matters more than manual adjustment. Ships flat-packed with the seat, backrest, base, gas lift, casters and armrests separate, plus hardware and instructions for home assembly.