Abstract: An adjustment mechanism for a head restraint assembly in which the head restraint is supported on one or more posts having a plurality of V-shaped detent notches for engagement by a spring clip to hold the head restraint in place. The spring clip includes a V-shaped contacting portion having two legs which concurrently contact the surfaces of the detent notches to hold the head restraint in place. The lowest notch is a locking notch having an upper inclined surface and a lower radial surface while the lower surface of the spring clip contacting portion includes a cutout the upper edge of which contacts the radial surface of the locking notch to prevent removal of the head restraint post. The outer edge of the V-shaped contacting portion of the spring clip is rounded to reduce abrasion of the post surface coating.