Mirra 2

Mirra 2 by Herman Miller

Mirra 2 is the iconic butterfly back chair. It is described to be "lean, light, and as responsive as your own shadow". It is built to adapt to the movement of the person sitting. There are two back options: the Butterfly Back or TriFlex. The Butterfly Back uses a fabric layer and polymer veins. This acts like a suspension membrane. The TriFlex is much easier to clean because it does not have a fabric layer.  

https://www.hermanmiller.com/products/seating/office-chairs/mirra-2-chairs/