Slip size is an important factor affecting the performance of sliding doors and Windows and water tightness, and is also an important factor affecting the closing force of doors and Windows. Wool top specification is too big or erection wool is exorcise, not only assemble difficult, and make door window moves resistance increases, especially the first resistance when opening and the final when closing is in place resistance is larger. The specification is too small, or vertical woof height is not enough, come out easily outside groove, make the sealing performance of door window reduces greatly.