Single-hung or sash windows have a fixed top sash with a bottom sash that slides up and down for ventilation. Hidden balance springs offer a clean look and allow for the window sash to be opened and closed effortlessly. Because the sash doesn’t protrude, they are a perfect choice for high-traffic areas such as decks and walkways. Commonly used in window openings that are taller than they are wide, the sash will self-level in any position at which the latch is released. The screens are located on the outside of the sash and are easily removable from inside the home when desired.