Herman Miller Aeron Ergonomic Size A  Which is a Smaller Size Black /Grey. Max Seast Height 50cms 2 Lever 3 available 
These Chairs are considered to be one of the best chairs on the market.. I have other Sizes on other listings 
The Herman Miller chairs are in a good condition minor marks only. Odd minor paint chips to frame Read up on chairs and see the outstanding reviews
They are Height Adjustable. And have  seat tilt  the arms are big for comfort. And with Tension  control The chairs are built for maximum comfort. Built in lumber support on the back. Mesh back and seat. Brilliant chairs at a good price