The OEM Herman Miller Classic Aeron Chair BackFrame Size B – 3D01 is a genuine replacement part for the iconic Herman Miller Aeron chair. This backframe is designed for use with Size B chairs, providing a sturdy and comfortable support for the back of the seat. As a genuine product from Herman Miller, you can trust in its quality and durability, ensuring a seamless and ergonomic seating experience for office and desk chair users. The back frame is for sale. Not the actual chair.