Had asked my PA to go back office to have a look.
All the chairs come with just allen keys, the back rest and the bottom seating area.
Posturefit is just a separate add on, the chair model are all the same, unless is the basic model.
We have a few sets of Posture fits in the office,here's what inside and pages of the installation guide.
All the chairs i think were packed by HM themselves.
I think the problem is for some reason, they separate the posturekit from inside the box.
Normally last time when i had it, it's altogether but this time, perhaps due to quantity, they packed all the posturefit into a single carton. Which they lost it during transit and i'm still chasing it.
Hope this clarifies this particular issue.
For those who wants to change from Posture kit to lumbar sets, let me know too.
As i've extras, do pm me. Will refund the differences.
Lumbar pad is good for those who likes to lean backward slouch a little, posture fit is for those who wants to stabilise an upright position.