The sash frame forms the movable part of a window and holds the glazing or infill panel. It is connected to the fixed outer frame via hinges and can be rotated, tilted, or slid depending on the hardware system. Geometric precision of the sash frame is critical for the tightness and functionality of the entire element. Materials include wood, PVC, aluminium, and wood-aluminium composites. The profile geometry significantly influences thermal insulation properties and the visible face width. Continuous sealing profiles between the sash and outer frame ensure air and driving-rain tightness in accordance with applicable standards.