The extensible bolt with front lever guarantees the anti-burglar function of double sashed window. The lever can’t be opened pulling it from the outside: the closed sash avoids the lever movement. The front movement allows to exercise more force to move many points of closing on the second sash. The lever has a movement of 180°: this means the fi rst sash can be closed even with the lever opened on the second sash, avoiding damages on the lever itself. To ensure the anti-burglar security on the higher corner drive, there is a device that advises about the lever rod status. The 180° opening movement of the lever make it suitable for windows with three sashes.