The Line of Chords Scale rule incorporates a scale from 0° to 120° in 1/2º increments.Two centre dots are provided, one on each blade and, with the aid of dividers, the rule can be set at any angle, or an existing angle can be determined.The circumference scale indicates the circumference by measuring the diameter.Packed in display wallet.600mm (24 in) Length.Sub divided mm and line of chords scale one side.Sub divided mm and circumference scale in mm other side.