Be mindful that in order to fit them you have to 'break the seal' between the upholstery side sqaub and the back panel - and once this is done it is near impossible to refit it fully.
If you have a rear cup holder fitted to your A2 (or if you intend fitting one) it is not possible to fit the Kamei armrest as the base mounting takes up space required by the cup holder.
Look at this thread. In french but you have pictures and references. I did the modification to my wife's car. If you have questions do not hesitate. That's the wife car and the tutorial was done by me.
After 1 year with the armrest, we just have one conclusion: NICE. Couldn't do without it anymore. Solid. No problems whatsoever. We rest both elbows (wife and meself) sometimes resting the weight on the elbow/arm/armrest to reposition ourselves. Very happy with the mod. Worth the money spent.