Abstract: A sleeve for a vehicle seat head-rest, including a hollow body which has a first cavity to receive said head-rest, and of which the upper end is surmounted by a top part, in which is formed a second cavity; a locking device adapted to move between a locking position in which it projects into the first cavity and an unlocking position, said device being biased towards its unlocking position by an elastic return means; an unlocking thruster adapted to move in order to push said device, wherein the second cavity issues to the exterior of the top part by an opening of which the size does not enable the insertion of a human finger and in that, over at least a portion of the travel necessary for moving said device from its locking position to its unlocking position, the thruster is positioned entirely within said opening.