Replacement Seat for Herman Miller Classic Aeron Size B Medium (Black Mesh). Fits Your Herman Miller Chair – Measuring 20.25 inch Width x 18 inch Depth x 6 inch Height, our Herman Miller Aeron replacement parts are designed to fit any Classic Aeron chair size B. Replace your old chair seat with great ease! Tough & Durable – Our Aeron Seat Replacement parts feature a reinforced, heavy-duty frame to ensure that it won’t break, crack, or get damaged easily. Sit on your new cushion without worries! Sit Comfortably – This seat is made of filament which offers fantastic ventilation, so you can stay cool all day. Our seat’s black mesh fabric also matches the mesh of Herman Miller Aeron chairs. Ready To Use – With this new Replacement Seat, there’s no need to assemble mesh, and foam required. The seat itself comes ready to install so you’ll only need a few minutes to revamp your Herman Miller Classic Aeron desk chair. Any product you return must be in the same condition you received it and in the original packaging. Please keep the receipt. We usually respond within 24 hours on weekdays. Thank you for shopping at our store.