upper edge of the lower track to the true ceiling of the upper track thereby permitting the fixed and the sliding frames to be raised up into the extra deep upper track so that they clear the upper edge of the lower track then the frame can be pulled or pushed out or in clear of its lower track or lowered and cleared of its upper track thus the frame is completely removable for any purpose such as repair replacement or entrance by an intruder these essential features are most commonly overlooked or not realized by occupants but not so by potential intruders the latter may use a strong flat tool such as a screwdriver or tire iron to lift either the screwed in place fixed frame or more easily to lift the sliding frame which is not screwed in place but only has a very small indoor latch and which automatically unlatches when the sliding frame is lifted at the latch end approximately one quarter to one half inch in accordance with one prior art method a small percentage of occupants attempt to keep intruders out by installing a stud bolt or screw vertically in the upper track with its exposed end extending down one quarter.