The invention relates to an electromechanical structure of an extendable electrical device comprising a body part (300) and a sleeve-like grip part (301). The smooth longitudinal movement between a retracted and extended position is effected by a clockspring in a spring barrel (302). A belt is wrapped around the barrel, and a slide part (306) is attached to the free end of the belt. When the device is retracted, the slide part with the belt slides along a longitudinal groove (304) made on at least one side of the body part until the slide part is interlocked. In response to pushing a releasing element, the interlocking is released, whereupon the belt is wrapped around the barrel and the body part slides smoothly to extended position.
