Abstract: A window includes a hollow extruded sash and a hollow extruded frame. The arrangement includes a pair of sashes which may slide up and down to permit opening the window and which may pivot horizontally to facilitate cleaning the window. In addition to the locking means generally provided at the top wall of the lower sash, locking means are provided along the side walls to provide additional stability for the arrangement while maintaining a tighter seal. The side walls include slots into which open-faced housings are snapped for receiving the locking members.