National Hardware N183-699 818 Sliding Window Movable Stops in Aluminum, 2 piece,National Hardware,N183-699" /> Aluminum, patio door/window movable stop Will lock in a closed or ventilated position It will lock in a closed or ventilated position, wing nut design ensures positive locking It will lock in a closed or ventilated position Wing-nut design ensures positive locking No tools needed to install