Herman Miller Aluminum Aeron Executive Chair Highly Adjustable with PostureFit Lumbar Support, Leather Arm Pads Tuxedo Grey Black Pellicle - Large Size (C) Home Office Desk Task Chair 12-Year Warranty covers everything that makes a Herman Miller Office Chair--including casters, tilts, pneumatic cylinders, and all moving mechanisms. Herman Miller Aluminum Aeron Executive Chair Highly Adjustable with PostureFit Lumbar Support and Leather Arm Pads - Large Size (C) Tuxedo Grey Black Pellicle Home Office Desk Task Chair Highly Adjustable Model with Fully adjustable Arms, PostureFit, Forward Tilt, Rear Tilt Limiter, Aluminum Frame, Tuxedo Grey Black Pellicle and Leather Arms. The Aeron chair by Herman Miller is, simply put, the best ergonomic chair you can buy.