A retaining device includes a base (51) extending in a longitudinal direction and presenting a top face (511) and a bottom face (512); and a plurality of retaining elements extending from the top face (511) of the base (51), each of the retaining elements being formed by a stem (52) surmounted by a head (53), the stem (52) having a bottom end (521) connected to the base (51), and a top end (522) opposite from the bottom end (521), the head (53) surmounting the top end (522) of the stem (52), and having a bottom face facing towards the base and a top face opposite from the bottom face.