In trailers with a platform having fold-down side panels (4,6), it is often a requirement that fasteners (2) holding the fold-down panels (4,6) in unfolded position have a double safety arrangement.

This purpose is achieved with a fastener (2) including a base plate (8) on which is provided a handle (12) with a locking hook (14) and pivoting on a journal (10), where the handle (12) is displaceable in the longitudinal axis of the journal and spring loaded in direction of the base plate (8), where at least one projection (18,20) or cutout (30) on the handle (12) and the base plate (8), respectively, includes interacting pin-formed projections (28) and cutouts so that the fastener is double secured, as the pin (28) on the base plate (8) is brought to engage the cutout (30) on the handle by the spring load on the handle (12) when the locking hook (14) on the handle (12) engages an eyelet (16) interacting therewith and disposed on an adjacent panel (6). Release of the panels (4,6) may be effected by a combination of a lateral pull and a turning movement of the handle (12), whereby the locking hook (14) is released from the locking eye (16).