A frame member of a vehicle seat and an adjustment arrangement for a seat belt webbing device mounted on an upper end of said frame member, the adjustment arrangement comprising: a webbing guide (68, 70) disposed at the upper end of the frame member, and provided with a guide slot for guiding a seat belt webbing therethrough; a bearing block arrangement mounted to the frame member; a latch plate spaced from the bearing block arrangement and secured to the frame member, the latch plate being formed with a series of vertically spaced slots; a height adjustment frame extending downwardly from the webbing guide into the frame member; a release member mounted to the webbing guide (68, 70), and provided with a latching tooth which is selectively engageable and disengageable with one of the slots in the latching plate; and a first spring engaged with the release member for normally urging the tooth into latching engagement with the one slot in the latching plate for maintaining one vertical position of the webbing guide (68, 70) relative to the upper end of the frame member, wherein engagement of the release member against the bias of the first spring disengages the tooth from the one of the slots in the latch plate enabling the height adjustment frame, the release member, and the webbing guide (68, 70) to be moved to a second vertical position relative to the upper end of the frame member as defined by another one of the slots in the latch plate, characterised in that a disengagement of the release member causes the tooth to engage and be in locking engagement with the other one of the slots to maintain the second vertical position and prevent upward and downward vertical movement. a webbing guide (68, 70) disposed at the upper end of the frame member, and provided with a guide slot for guiding a seat belt webbing therethrough; a bearing block arrangement mounted to the frame member; a latch plate spaced from the bearing block arrangement and secured to the frame member, the latch plate being formed with a series of vertically spaced slots; a height adjustment frame extending downwardly from the webbing guide into the frame member; a release member mounted to the webbing guide (68, 70), and provided with a latching tooth which is selectively engageable and disengageable with one of the slots in the latching plate; and a first spring engaged with the release member for normally urging the tooth into latching engagement with the one slot in the latching plate for maintaining one vertical position of the webbing guide (68, 70) relative to the upper end of the frame member, wherein engagement of the release member against the bias of the first spring disengages the tooth from the one of the slots in the latch plate enabling the height adjustment frame, the release member, and the webbing guide (68, 70) to be moved to a second vertical position relative to the upper end of the frame member as defined by another one of the slots in the latch plate, characterised in that a disengagement of the release member causes the tooth to engage and be in locking engagement with the other one of the slots to maintain the second vertical position and prevent upward and downward vertical movement.