ENCRAFT Vertical Slider Windows, a traditional fenestration concept that has become the perfect solution for ancillary frames when the opening aperture is taller than width i.e. reference golden ratio 1: 1.618, and 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 because of requiring less space enabling the modern uPVC vertical slider to fit perfectly into both aperture types, straight through or reveal.