USHA Vertical Slider Windows offer a traditional fenestration concept perfect for ancillary frames when the opening aperture is taller than width, i.e., following the golden ratio 1:1.618. These windows are ideal when one opening sash is required for ventilation and/or fire escape. Its simple operation is based on a pair of frame-specific, site-tensioned, spiral balances that can hold the sash open in any position. The spiral balance technology has successfully replaced the traditional weights and pulley method, requiring less space and fitting perfectly into both aperture types, straight through or reveal.