Herman Miller Classic Aeron Chair PostureFit Support Kit - Graphite - Size A Plastic Made in USA Provides back support at the base of your spine, or sacral region, helping your pelvis maintain a natural forward tilt to prevent slouching Keeps your spine in healthy alignment to help eliminate lower back pain Solution for a healthful posture and significant improvement toward lower back support in a work chair Compatible with all sizes (A, B, or C) of Classic Aeron Chair and Classic Aeron Stools, provided the chair has a Tilt Limiter option 12-year Herman Miller warranty