Back Rake – This is where the back is adjustable by tilting backwards and forwards. Will normally include back height adjustment.
Independent Action (ISB) – A simple but very effective action where the seat and back will move independently of each other. Some form of weight tension control will be included.
Synchronised Action (Synchro) – By far the most common type of action where the back will move backwards and forwards in conjunction with the seat, normally at a ratio 2.5:1 Weight tension will be included by use of an under the seat or side operated adjustment.
Intelligent Action – a relatively new type of chair action where the seat and back will move independently of each other but without the need to set a weight tension.
Body Weight Synchro (BWS) – Another new type of chair action which operates in the same way as the normal synchro, but will automatically choose the right weight tension (this can be fine tuned in most cases though).
Seat Slide – Does what it says and moves the seat backwards and forwards, usually by around 50mm
Spindle – This is simply the ‘gas’ (spring) operated column that allows the seat to be moved up and down.
3D Arms – A slightly confusing term as all it means is that the arms will not only go up and down, but will also slide backwards and forwards as well as be adjustable in width.
4D Arms – These will do the same as above but will also have arm pads that will swivel either part or all the way around.
Inflatable/Adjustable Lumbar – Normally this is by inflating an airbag hidden in the back pad of the chair or by having a tension bar that will be adjustable in height.