Abstract: An elongated element for the frame of a panel system comprising a flexible sheet material includes a main profile to which an auxiliary profile is associated. The auxiliary profile is provided with means for anchoring an edge of the sheet material and it can be moved with respect to the main profile as a result of the driving of position control screws. The main profile is adapted to be fixed on the surface of a wall by connection means engaging a connection portion associated to it. The position control screws have a control formation which can be reached from the outside of the frame, when the main profile of the elongated element is fixed to a wall and the sheet material is anchored to the auxiliary profile.