Horizontal Sliding Windows are typically made of 2 or 3 sash in a frame. When there are 2 sash there is one operable sliding sash that slides over a fixed sash. The fixed sash is typically located on a plane towards the exterior while the operable sash operates on a track located towards the interior. On a sliding window with 3 sash there are two operable sash on either side that slide away from the edges towards the center over a fixed center sash. The rollers in the operable sash can be adjusted for ease or operation.