A rack and pinion are mounted on a casement window frame to operate a vertically disposed polymeric latch keeper. The moveable rack includes a plurality of teeth which are engageable with latch keepers spaced therealong. The pivotable window section includes latches which are rigidly affixed thereto. Thus when the window is closed a pinion can be rotated and thus drive the rack to engage the latch keepers into mating engagement with the latches for security and wind load resistance. The method of installation utilizes frangible spacers affixed to the latches for quick and easy alignment with the latch keepers.