element or stand 4 in the deployed position and the retaining of the carriage 17 in the retracted position retains the support element or stand 4 in the stowed position more particularly in this example the carriage 17 includes a flange 45 which when moved over the resilient ramp sections 43 and 44 becomes retained or reversibly locked by the resilient ramp sections 43 and 44 to retain the carriage 17 in either the extended or retracted position moreover each ramp section 43 44 includes ramps which have a generally saw toothed shape and are arranged in opposing direction to one another so as to allow the carriage 17 to easily proceed from a position between either of the ramp sections 43 44 and move over a respective one of the ramp sections 43 44 to become retained by the respective ramp sections 43 44 in one of the extended or retracted positions the generally saw tooth shape of the ramps of the ramp sections 43 44 assists to retain the carriage 17 in the extended or retracted positions the ramp sections 43 44 are sufficiently resilient for example being formed from a plastic or thin sheet metal to allow the flange 45 of the carriage 17 to proceed against the saw tooth.