The assembly (10) has a cylindrical body (11) extending along an axis (12). An internal cavity comprises a slide that is arranged parallel to a plane (21) passing through the axis of the body. Two wings (16, 17) are placed in the cavity. A side of the wings slides between a retracted position and a partially deployed position and comprises an internal end and external ends (18, 19). The assembly is designed such that displacement of the external ends is tangential to a plane perpendicular to the axis of the body when the external ends cross a side opening (20).
