Abstract: A blind fastening method and device for use in clamping a component to a support plate, in which the fastener device is taken through aligned openings in the component and in the support plate, and comprises: a slotted sleeve; an apertured sleeve head at one end of the sleeve; a threaded fastener portion which can be taken through the apertured sleeve head and the sleeve; a tightening fastener head for tightening the fastener portion; and a diverging sleeve-expanding head mounted on the fastener portion and engageable with the opposite end of the sleeve to expand the latter radially outwardly to anchor the sleeve; in which the sleeve head has an off-set formation engageable to a tool which prevents rotation of the sleeve head while the fastener head is being tightened.