Single Slider Window operates horizontally (side to side). One sash doesn`t open and the other sash moves. Included is a screen that covers half the window. The moveable sash moves sideways and can tilt into the room for easy cleaning. Added features such as extra weather-stripping and a sash encapsulated into the frame will ensure that drafts cannot break through. Our windows are manufactured to such tight standards that when locked, there is virtually no slop or movement.