The present invention relates to a device for adjusting and locking a strap. It also comprises a timing control unit to synchronize between the columns to allow all pixels of a single row to be lit at the same time. Instead, this type of information is made available only to a user’s personal device that the user carries andor trusts. On one of the decks is located a propulsion unit and horizontal and vertical control surfaces. Each of these rules may be associated with a boundedly undefined condition.