4-ring binders

Four rings hold a sheet at four points, so papers stay straight and are less likely to tear at the holes. For thin sets choose Viquel Standard (black, dark blue) or the transparent Propyglass with a 2 cm spine; for everyday use the 3.5 cm College binders in white, yellow, red and green. For large volumes there are white Panta Plast binders, 7 and 8 cm, with D-rings that keep the sheets in an even stack.