uPVC window sills are available in 85mm, 125mm, 150mm, 180mm and 225mm widths (150mm being the most popular size), and various colours.
They are designed to match Spectus / GAP / Rockdoor profiles amoungst others and come with a full range of joints, angles and corners. Being made of uPVC, the Window Sills resist most scratches and stays looking great as long as your uPVC Window.