It's a standard.

Fully automated calibration system; all-round adjustability of the seat and back rest position; seat height and the foot support; remote control (DIRECT CONTROL BM) for electronic adjustments; lifting aid and ergonomic fixation of the thighs supported by gas dampers.
This may sound like some lengthy list of options: as a matter of fact, everything mentioned here comes as a standard with the Back Module. All options included.