These chairs are really good quality for less than £30 each. They are light but quite strong and neat and importantly, they are very comfy. They do not stack - unfortunately, I wanted stackables but got mixed up with looking at so many chairs. 
Self Assembly tip....
Every chair assembled properly but I recommend that you first assemble the two sides and the crosspiece and then fix the seat on to that before finally slotting in the chair back. However, fix in each and every bolt very, very loosely with the allan key until the chair is fully assembled and then tighten up completely at the end. If you tighten up as you go along, you will end up with holes that do not line up. This happened to me on chair no.1 so I had to unravel and start again.