Features: Engineered for marine navigation, this 450mm parallel ruler combines high transparency acrylic and polished copper spacers, ensures accurately azimuth measurements and clearly scale visibility on navigation chart. Features copper acrylic construction with oxidation resistant polishing, the mutifunctional parallel ruler offer flexible operate and stable alignment for seamlessly chart plotting in demanding marine environment. Suitable for professional navigators, marine cartographers, and sailing enthusiasts requiring professional parallel drawing ruler measuring tool for complex course calculation during voyages or detailed charting task. Widely used for maintaining precisely bearing line during onboard navigation planning, coastal map exercise, or educational marine navigation workshop where millimeter accuracy matters. Its light weight design withstands saltwater exposure while providing effortlessly portability between ship bridge, navigation station, and training facilities. Specifications: Color: Clear Component: Acrylic, Metal Size: Approx. 45x7.50cm/17.72x2.95in Weight: Approx. 310g Package Includes: 1Piece Parallel Ruler note: 1.Please allow 0-1cm error due to manual measurement. Be sure you donot mind before bid. 2.Due to difference between different monitors, the picture may not reflect the actual color