When measuring the gearing for a Tilt and Turn window, it is not the overall size of the opening sash window you are seeking, but the size of the rebate. This is where the metal strip goes around the sash. As the gearing is designed to fit various sizes of window sash in both its width and its height, so that when you receive the parts, you may have some of the mechanism to cut down to size to engage it with the corner drives or the top scissor mechanism. View our videos on how to repair Tilt and Turn windows below. How To Replace Tilt & Turn Window Gearing Part 1: How To Replace Tilt & Turn Window Gearing Part 2: