Prime-Line H 4128 Single or Double Hung Window Sash Cam, Top Mount (2 Pack)

This plastic sash cam fits onto the upper top sides of the window (vent) that is sliding up or down. The sash cam and window then rest on the top guide of the sash balance. It has dimensions of the top being 1 inch wide by 5/8 inch deep and 1-5/16 inch tall. Width of this top guide needs to fit correctly in the window's track frame in order for it to slide up or down properly, and the depth allows the window to correctly rest on the top guide of the sash balance.