The 18-inch (45.72cm) Aluminum Arms Parallel Rule feature aluminum arms that join two clear acrylic rulers inscribed with a protractor scale. An essential item in any proper navigation kit, these rules are used to plot direction on a nautical chart from any convenient meridian or compass rose. The two straight-edged rules are connected to maintain the same angle. By walking the rules across the chart and securely holding down the non-moving rule, you can effectively plot a course. 18-inches (45.72cm) long Protractor scale Sturdy clear acrylic with aluminum arms Protective plastic sleeve Length: 18 in (45.72 cm) Width: 2.6 in (6.6 cm) Height: 0.5 in (1.27 cm) Weight: 0.5 lb (1.27 cm)
