DRAW large CIRCLES or arcs that are beyond the limit of the dividersIt consists of a bar with two movable heads Wing compassParts of the wing compass are shown in Figure.The legs of the wing compass are hinged at the top or joined with spring and forced open or CLOSED by turning a knurled knob that attaches to a threaded POST spanning the legs.Spring CompassThe spring compass is used to draw circles and SMALL arcs of 25 mm radii. The screw and nut arrangement is used to set the radius accuratelyWhen using spring type wing compass the measurement once taken will not vary while marking.The two legs of the compass should always be equal in length. The compass is specified by the type of joints and length.