Abstract: The invention relates to a stabilising device (120) for an assembly which includes two shape memory alloy wires (104, 106) adapted to operate in conjunction. The stabilising device (120) includes a rocker plate (108) for attachment to each of the shape memory alloy wires; the rocker plate (108) is adapted to pivot when one shape memory alloy wire (104 or 106) is subjected to a stress greater than that to which the other shape memory alloy wire (106 or 104) is subjected, in order to reduce the stress on the first-mentioned shape memory alloy wire. The invention further relates to a fastener (60) including a stud (54) having a locking cavity (56), an aperture (58) adapted to receive the stud (54), a locking means (teeth) (62) adapted to engage the locking cavity (56), a shuttle (66) rotatable by a rotating means including material adapted to contract when activated and a plug (87) slidable within the shuttle (66) to close off the aperture (58) when not occupied by the stud (54).