Abstract: A fastening device for wings, specially for windows, for lockable closure and lockable holding of the wing in one or more opened positions, which device comprises a movable arm which has one end connected to the wing of the window. The arm forms a channel and has a longitudinal slot in communication with the channel, and a plurality of spring loaded locking means are placed in a row in the channel. Upon introduction of a latch through the slot in an upward direction into the channel between two locking means, the latter are moved apart under spring action, whereupon at least one of the two locking means engages an engagement surface of the latch inserted in the channel. A screw spindle is screwed into the other end of the arm, and the two locking means are arrestable, in the position in which they engage the latch introduced into the channel, by such a displacement of the screw spindle that the spring action is abolished.