This style of windows allows the customer to operate the window by sliding sashes left or right or horizontally, with the locking mechanism located doirectly in the middle of both sashes the lower sash upwards to open and downwards to close with locking mechanism positioned at the top of the sash. The difference between a single and double hung is the upper sash which operates in a double hung style. This comes with the advantage of easy cleaning by allowing the customer to wilt in the sashes to access both sides of the glass.