The Parallel ruler is used to draw lines and plot directions on a nautical chart. Crafting ruler provides precise measurement with strong plastic links which provide the right amount of tension for drawing a line parallel to another line or reference point. Scale ruler with a transparent finish allows viewing through to the page while you work with non-skid pads and non-magnetic parts. The ruler is split in half and the two halves are joined together by pivot points with strong material arms and metal handles. Usually they are made of extra strong, crystal clear acrylic, it is ideal for artists, designers, architects, engineers, and students.