Genuine Herman Miller Aeron Seat Back – Size B – USED but good condition. This is an authentic used seat back from a Size B Herman Miller Aeron chair, including the original Pellicle mesh and frame. Perfect replacement if your mesh is torn or the back frame is cracked. ? OEM part, not aftermarket?? Size B – standard size (fits most users)?? Mesh is in excellent condition – no rips, sagging, or holes?? Frame structurally sound, no cracks?? Compatible with all classic Aeron B chairs. Note: This listing is for the seat back only (no lumbar pad or mounting bolts included).